Department no. 103 Hon. Lance A. Ito, Judge
APPEARANCES: (Appearances as heretofore noted, Mr. Thompson also being present representing the Defendant; Ms. Kahn also being present representing the People.)
(Janet M. Moxham, CSR no. 4855, official reporter.)
(Christine M. Olson, CSR no. 2378, official reporter.)
(The following proceedings were held in open court, out of the presence of the jury:)
THE COURT: Back on the record in the Simpson matter. Mr. Simpson is again present before the Court with counsel. I see Mr. Neufeld, Mr. Scheck, Mr. Bailey, Mr. Thompson. I am not acquainted with this gentleman.
MR. THOMPSON: This is Dr. William Shields, your Honor.
THE COURT: Good morning, doctor. The People are represented by Mr. Clarke and Ms. Kahn. The matter is here for a 402 hearing this morning regarding the interpretation of mixtures. Miss Kahn.
MS. KAHN: Your Honor, I believe Mr. Clarke is going to address the Court on this issue.
THE COURT: Mr. Clarke.
MR. CLARKE: I think just as prefatory comment, I think what we need to look at is the situation we are in at the moment with regard to this particular type of evidence. In particular, if the Court will recall, with respect to the original witnesses in this case, in particular Dr. Cotton and Mr. Sims from the Department of Justice, it was not either their intention or our intention of providing to the Court, or providing to the Court in this case, frequency numbers about mixtures, and that was argued before the Court and ultimately resolved by this Court with the Court's finding that indeed frequencies as to these mixtures were to be presented. And we have operated accordingly since that time. The Court may recall a little bit about the history of that, and in fact there was a good deal of scrambling, for lack of a better term, with the original witnesses in particular, Dr. Cotton, to be able to obtain frequency numbers to describe these mixtures in some fashion. It was determined in the course of that work, as far as mixtures were concerned, that in fact Dr. Weir would describe mixtures and attach frequencies to them. At the point we are at now, it is our intention to present, through Dr. Weir, frequencies with regard to these mixtures that are the product, or actually the result would be a better word, of summing individual possibilities of genotypes in both two-person mixtures, in other words, assuming that a mixture was from two different individuals, as well as three-person mixtures, assuming that a mixture was the product of three different contributions from three different persons. With respect to that procedure, Dr. Weir is perfectly prepared to describe that to the Court and in fact we think we can do that through Dr. Weir in a fairly very understandable fashion. I think we need to reexamine, however where, we are in terms of this hearing. This hearing involves again, if it is granted by the Court, a determination by this Court apparently as to what method of adding frequencies using the summing technique is appropriate.
And we don't feel--in fact, we feel very strongly that is not subject to a determination by this Court in terms of a 402 foundational hearing because it is apparent that Dr. Weir, and as far as our position is concerned, that his method of determining these mixture frequencies is the most appropriate fashion in terms of the summing technique. And it is apparent the Defense feels that a different technique is in fact the appropriate one. That I think is clearly the type of matter that has to be resolved by the trier of fact, not resolved by the Court in terms of a 402 hearing as to which is the more appropriate method to proceed by, assuming that it is in fact a summing technique which the Court will hear clear evidence that it involves adding up different genotype frequencies. I think that is particularly important when the Court recalls that this Defendant completely waived any admissibility about DNA typing evidence. That we felt, as we broached to the Court many weeks ago at this point, certainly cleared the way for the type of testimony, and in fact not even assigning frequencies to mixtures in this particular hearing, but the Court ruled otherwise. So here we are today, the Defense still has not or still has not at least attempted to reverse their waiver of this evidentiary hearing, this Frye hearing in terms of admissibility that we know applies to population frequency data as well, and in this hearing apparently seeks to convince this Court that our expert's method of adding genotypes is not a correct one. That again I think, as the Court should realize, is clearly a matter of weight for the jury; not a matter of admissibility. In many respects, it is not different to this Defendant during testimony about DNA typing itself--itself, objecting to the fact that a procedure wasn't performed properly; therefore, the Court should have an evidentiary hearing. We know that wasn't done in this case and I feel confident the Court would have quickly denied the Defense any opportunity to contest that matter in terms of a foundational hearing because of the waiver that had already occurred. This is not different with regard to these population frequency data. So again it is our position the Court has no need whatsoever for an evidentiary hearing. If the Court would like an explanation from Dr. Weir about how he summed these different genotype possibilities, that can be done, certainly, and perhaps may satisfy the Court that in fact there is no need for a hearing whatsoever.
But again, it is our position that we are ready to proceed in front of the jury, when the jury is available, with Dr. Weir's testimony about adding genotypes together in terms of these mixture frequencies and we feel that the Court can conduct that hearing--I'm sorry--can allow that testimony to be presented with no hearing necessary whatsoever.
THE COURT: All right. Thank you. Mr. Thompson. A hearing to determine whether we are going to have a hearing.
MR. THOMPSON: All right. Well, I think Mr. Clarke has correctly characterized what the Prosecution is doing is scrambling. At this point it is not entirely clear to us what they intend to present. They early on presented a report--I guess earlier on, in the middle--let me trace the--let me trace the history of what has happened here. We got a report from Dr. Weir in May 11--on May 11th that was presenting likelihood ratios, to characterize these mixtures, and we registered our objections. On May 31st there was another draft report also using likelihood ratios and saying likelihood ratios are essential to characterize mixtures. On June 20th, that is Tuesday, we got yet another report saying likelihood ratios are essential. We were all geared up to challenge likelihood ratios when we learned Tuesday that they were presenting frequencies instead and we got a report on their frequency method. Well, it has been drifting in. We got some of it yesterday morning, some of it was faxed to the hotel last night and corrections were just given to us this morning, so we are just getting this revision that presents what they are calling frequencies. In fact, it appears to me the frequency--what they are calling frequencies are in fact the same numbers that they were calling likelihood ratios earlier, they are just recharacterizing them. Now, as far as whether a 402 hearing is necessary, I think one is necessary to allow you to rule on the foundational objections that we are raising to whatever it is that they are going to present, without which we are still somewhat confused. I think it is clear that the presentation of likelihood ratios is unprecedented. Presentation of frequencies in connection with mixtures or the proper approach to computing frequencies in connection with mixtures is again an issue that has not been--that has not been discussed in the appellate case law and an issue about which there appears to be some scientific controversy. It is our position that if they do present statistics in connection with mixtures, which they are required to do under this Court's ruling and we believe under the laws of this state and particularly under People versus Barney, that they must computer those frequencies according to an accepted method. And we are taking the position that the accepted method is the National Research Council's method which we have discussed with you earlier. I think it is quite clear, from what we've seen from their reports, that they are not computing these mixture statistics according to the National Research Council's method; they are using a different method, and they are using a method to which we have a number of substantive objections that go beyond the general acceptance and following of correct procedures. In particular, we take the position that the way in which they are calculating these frequencies is argumentative, that it incorporates assumptions that are consistent with Prosecution evidence in this case, that it invades the province of the jury by presenting argumentative conclusions in the guise of expert testimony. We also contend that this evidence is objectionable because it fails to take into account all important variables that should affect the conclusions that they purport to be drawing from it and therefore it is objectionable under People versus Chela, a case we cited to you in our notice of objection filed earlier. We will argue that it is extremely prejudicial and therefore excludable under 352 as well. In order to rule on all of these objections, these latter objections having nothing to do with Kelly and having nothing at all to do with the waiver that occurred with respect to DNA evidence, per se, you are going to need to hear some testimony. We are going to need to cross-examine Dr. Weir to find out what exactly it is that he is purporting to present. And then we would like to present expert testimony from Dr. Shields who will tell you that what--what Dr. Weir is doing appears not to be the National Research Council method and that it has problems, which he can explain. So all of these--these factual issues need to be put on the table in order for you to rule on the--on the objections. As far as waiver goes, I mean, when we withdrew our objections to the admissibility of--of DNA evidence in January, no one was contemplating likelihood ratios and the of ever mixture statistics hadn't been raised at that point at all. And certainly the fact that we withdrew our objections to DNA evidence at that point does hot give the Prosecution license to present to the jury any kind of--any kind of scientific testimony they choose, regardless of its scientific validity and regardless of whether it is prejudicial or misleading or argumentative. All of these objections are maintained. Those are trial objections and foundational objections which in your rulings you recognized are preserved. Therefore a 402 hearing is necessary and we would like to proceed with it.
THE COURT: All right. Any brief response, Mr. Clarke?
MR. CLARKE: Yes. Thank you, your Honor. I think the Court has already been made aware that it is not our intent to use likelihood ratios and I think everyone who has been involved in this over the last several days is aware of that fact and in fact the particular summing type of frequencies for these mixtures that is going to be sought to be offered in front of this jury is a summing technique, it is a summing technique that is described by the NRC report. Who while describing it in somewhat vague fashion, clearly in our view covers the exact technique used by Dr. Weir in this particular case. But most importantly, I think Mr. Thompson has brought up the very words that show why this hearing shouldn't be conducted and that is general acceptance. He specifically mentioned an allegation that the method used here is not generally accepted, and those are exactly the terms that were waived or the type of foundational showing that was waived by this Defendant many months ago. These are factual issues, as he just described them, which are the exact same types of issues that are to be decided by juries and not by courts in terms of admissibility. There is at this point, based on the offer or at least the comment by counsel, absolutely no need for a 402 hearing. If the Court would like to ensure that the technique used to be testified to by Dr. Weir involves a summing technique, we would be happy to have him describe that and it wouldn't take very long. But I think in terms of an admissibility hearing, this Defendant again gave up that right many, many months ago.
THE COURT: All right. Thank you, counsel. Counsel, I think that the unfortunate situation we have here is that this is a relatively novel situation. There are no reported cases that deal specifically with mixtures in the forensic setting. Although there is--there are reported cases in the analogous paternity setting where obviously by definition you have mixtures, there is--there does appear to be some controversy in the area that I have read about in my preparation for today's hearing. And the thing that concerns me most is whether or not this is going to be unduly confusing to the jury, so on the bases of both evidence code section 402 and 352, I'm going to require the Prosecution to present to the Court a foundational showing that this should be presented to the jury.
MR. CLARKE: Very well.
THE COURT: All right. So the burden is on the People. Mr. Clarke.
MR. CLARKE: Yes. Dr. Bruce Weir, please.
THE COURT: All right. Mrs. Robertson, witness.
Bruce Weir, (402) called as a witness by the People, pursuant to Evidence Code section 402, was sworn and testified as follows:
THE CLERK: Please raise your right hand. You do solemnly swear that the testimony you may give in the cause now pending before this court, shall be the truth, the whole truth and nothing but the truth, so help you God.
DR. WEIR: I do.
THE CLERK: Please have a seat on the witness stand and state and spell your first and last names for the record.
DR. WEIR: Bruce Weir, B-R-U-C-E W-E-I-R.
THE COURT: Mr. Clarke.
MR. CLARKE: Thank you, your Honor.
DIRECT EXAMINATION BY MR. CLARKE
MR. CLARKE: Dr. Weir, good morning.
DR. WEIR: Good morning, Mr. Clarke.
MR. CLARKE: Could you describe for the Court, please, the position that you hold currently.
DR. WEIR: I'm currently a professor of statistics and genetics at a North Carolina State University.
MR. CLARKE: Located in what city?
DR. WEIR: In Raleigh, North Carolina.
MR. CLARKE: How long have you been at that university?
DR. WEIR: I first went there as a graduate student in 1965. I've been on the faculty since 1976.
MR. CLARKE: Your Honor, I have what can be described as I believe a CV of Dr. Weir that I would ask be marked as--does the Court wish us to continue with the exhibit numbers?
THE COURT: Yes. This would be People's 40--
THE CLERK: 7.
THE COURT: 407.
MR. CLARKE: A copy of which has been previously provided to the Defense.
(Peo's 407 for ID = CV of Dr. Weir)
MR. CLARKE: Dr. Weir, showing you what will be marked as an exhibit shortly, can you describe what that is?
DR. WEIR: Yes. This is my CV.
MR. CLARKE: And I'm sorry, your Honor, I didn't catch the exhibit number.
THE COURT: 407.
MR. CLARKE: Thank you.
MR. CLARKE: All right. Dr. Weir, do you have a copy of your CV with you also?
DR. WEIR: No.
MR. CLARKE: All right. Could you tell us then and describe for the Court, if you would initially, your educational background?
DR. WEIR: I have a bachelor's degree in mathematics from the University of Canterbury in New Zealand, a Ph.D. in statistics with a minor in genetics from North Carolina State University and I spent time as a postgraduate research geneticist at the University of California at Davis.
MR. CLARKE: In particular you described your Ph.D. being in the area of statistics. What did that encompass, if you can briefly summarize that?
DR. WEIR: Well, it was fairly detailed examination of the methods in statistics, both the theory of statistics, the mathematical theory, and the appropriate means of analyzing data.
MR. CLARKE: All right. With the Court's permission it would be my request that the Court actually have the exhibit before the Court and then I have a copy that the witness can utilize as well.
THE COURT: Fine.
MR. CLARKE: All right. Dr. Weir, could you hand that to the Court.
THE COURT: Thank you.
DR. WEIR: (Witness complies.)
MR. CLARKE: As far as your employment history, could you describe that, please.
DR. WEIR: When I completed my postdoctoral period I returned to New Zealand as a senior lecturer in mathematics at Massey University. I remained there for almost six years and then returned to this country in 1976 as an associate professor of statistics and genetics and I have remained in that department, the department of statistics.
MR. CLARKE: During the time--and I believe you said that was a six-year period at the--in the department of mathematics at Massey University in New Zealand?
DR. WEIR: Yes, sir.
MR. CLARKE: What did you do during that time?
DR. WEIR: I did then what I do now. I teach statistics and statistical genetics. I conduct research in the appropriate ways of analyzing genetic data.
MR. CLARKE: What year did you start at North Carolina State University?
DR. WEIR: On the faculty it was in 1976.
MR. CLARKE: So almost twenty years at this point?
DR. WEIR: That's right.
MR. CLARKE: What have you been doing during that time period at the university?
DR. WEIR: I've been working very hard to develop statistical methods to analyze genetic data.
MR. CLARKE: In that position do you teach?
DR. WEIR: I do teach. I have taught general statistics courses. In recent years I have taught courses based on my book on genetic data analysis.
MR. CLARKE: Now, you have used this term "Genetic data" and you have also used the term "Statistics" as well?
DR. WEIR: Yes.
MR. CLARKE: How do those two relate to one another, if they do?
DR. WEIR: Well, we use statistical methods--statistics, as you know, can be applied to many different fields. My specialty is in applying statistical methods to data concerned with genetic entities. What we will be talking about today is the specific DNA markers used in forensic science. Those are of course just one of many types of possible genetic data.
MR. CLARKE: On your CV, and in particular on page 1, there is also a category listed as "Honors"; is that right?
DR. WEIR: That's true.
MR. CLARKE: Of those Honors that are listed, are there any of particular note?
DR. WEIR: Well, I think I'm most proud of two. I had a Guggenheim fellowship in 1983 of which I am proud, and then in 1992 I was given a named professorship at my university.
MR. CLARKE: Now, the Guggenheim fellowship, did that involve your conducting any research or other activities at another university other than your own?
DR. WEIR: Well, the fellowship enabled--it enabled me to take a year sabbatical and I went to the University of Edinburgh for a year and essentially brought myself up to speed on the current DNA methodologies.
MR. CLARKE: That was in what year?
DR. WEIR: `83, `84.
MR. CLARKE: While you were at the University of Edinburgh did your activity--and you have described getting yourself up to speed; is that right?
DR. WEIR: That's true.
MR. CLARKE: In what way, if you can briefly summarize that?
DR. WEIR: Well, prior to that period, although I should stress that my statistical methods have not changed since--have not changed direction fundamentally, but prior to 1983 I was concerned mainly with genetic data on protein polymorphisms. Since that time I've dealt more with DNA sequences and the molecular markers. It is just a change of emphasis. It is not that the methods of statistics have changed, but the language needed to describe the data have changed and I needed to be sure I understood all the terminology being used by the molecular biologists.
MR. CLARKE: When you described this transition, you are referring to this transition from the use of electrophoresis to type proteins into DNA typing itself?
DR. WEIR: Yes, that is correct.
MR. CLARKE: And I believe you also mentioned, as far as the other Honor of note, your current professorship; is that right?
DR. WEIR: Yes. It is a mark of distinction given by my university which I'm very proud.
MR. CLARKE: Turning to page 2, there are a number of professional societies listed of which you are a member?
DR. WEIR: Yes.
MR. CLARKE: Doctor, any of those societies which you would describe as--
DR. WEIR: I think the most relevant ones here were the American Statistical Association, the American Society for Human Genetics and the Genetic Society of America.
MR. CLARKE: You are involved in the area of publications; is that right?
DR. WEIR: That's what I do, yes.
MR. CLARKE: As far as publications, do you serve as an editor of any journals?
DR. WEIR: Yes, I do. I am one of the senior editors for our theoretical population biology. I'm responsible for the genetics paper in that journal. For a long time I have been on the editorial board for the journal of genetics and for the last two or three years I'm on the editorial board for the American Journal of Human Genetics.
MR. CLARKE: Again referring you to page 2 of your CV, you list a number of other publications of which you are either editor or associate editor?
DR. WEIR: There have been other journals. I believe I'm still on the editorial board for the journal of heredity and some other journals that are rotated off those boards.
MR. CLARKE: I would like to shift your attention, if I can, to scientific presentations. Are you involved in giving scientific presentations?
DR. WEIR: Yes, I am. It is a very important part of our work to disseminate our findings, both through publications, which of course is the most important, but a more immediate dissemination is at scientific meetings. And in the last--I guess since 1990 I have been very heavily involved in the statistics associated with the forensic uses of DNA and on the basis of my published work I am now being--I am now receiving several presentations to present at international meetings. I will be going to Spain in the fall for the International Forensic Human Genetics Conference and in the summer of next year to Edinburgh to the International Conference on Forensic Statistics.
MR. CLARKE: Prior to today have you actually been invited and lectured in conferences involving statistics in DNA?
DR. WEIR: Yes. There was a meeting in phoenix, I believe two years ago, and at the FBI academy there was an international symposium on the forensic aspects of DNA analysis.
MR. CLARKE: Have those presentations that you've given include various parts around the world?
DR. WEIR: Yes.
MR. CLARKE: In your role at North Carolina State do you also supervise Ph.D. candidates in this area?
DR. WEIR: That's right. One student in particular, Paul Maiste, completed a thesis under my direction in 1993 and we conducted a fairly extensive examination of the means for testing for independence and mark the various components of a DNA profile. His thesis was completed and it has been on the record since 1993. The first paper from the thesis appeared in print last week in the Journal of Genetica.
MR. CLARKE: I would like to turn your attention to what appears to be page 4 of your CV and beginning on that page are there publications listed of which you have either been sole author or co-author?
DR. WEIR: Well, starting on page 4 and then running some pages it lists my complete publication list, yes.
MR. CLARKE: That is approximately one hundred publications in total?
DR. WEIR: That's right.
MR. CLARKE: Do they include a range of topics?
DR. WEIR: Well, yes and no. They are all involved in statistical analyses of genetica. Some of them are purely theoretical. Some of them are applications of these methods to specific data sets, human, drosophilia, maize, mice. It doesn't really matter as far as my work is concerned what the organism is, whenever genetic data are collected, then I'm happy to be involved in their analysis.
MR. CLARKE: Have your publications included a substantial number dealing with human genetic characteristics?
DR. WEIR: Yes, in two different directions. What I'm primarily interested in is looking for associations of genetic markers with human diseases. I think that is very important and very exciting work and I've had several papers in that field. And as I said earlier, I have also been involved in the forensic arena recently, so I have had several papers targeted specifically to the kind of data used by forensic scientists.
MR. CLARKE: I would like to call your attention, if I could, to two publications in particular, the first on page 5 that I believe is labeled no. 29 titled, "Inferences about linkage disequilibrium."
DR. WEIR: Yes. That is a paper published in `79 talking about the methods to detect associations or lack of independence between elements at different genetic loci. It is--it is one of my--I think one of my important papers. It is just a foundation for a lot of our subsequent work.
MR. CLARKE: All right. When you use the term "Independence among loci," can you tell us a little bit more about what you mean?
DR. WEIR: Well, it goes back to Mendel's second law of course. What we are interested in knowing is if the information transmitted from parents to offspring at one locus, one region of the genome, is transmitted independently of information at different loci, different regions. For loci on different chromosomes we would expect to find such independence, although as I showed in my thesis in 1968, even loci on different chromosomes may have some slight dependence on their frequencies imposed by the size of the population and the mating structure. I'm digressing. The point is that we laid out in that paper some of the methods appropriate for detecting associations, regardless of the biological cause. And I think we need to stress that today. We are not interested in the biological mechanisms as much as in the consequences. What do the data look like? Do they exhibit independence and therefore may we proceed to use product rules? Or do they not show consistency with independence in which case we need to do something else?
MR. CLARKE: In other words, basically you are looking at whether or not different regions of DNA may be linked in some fashion?
DR. WEIR: Yes. I would prefer to use the word "Associated." Linked has the technical term and we are not talking about linkage. We are talking about associations.
MR. CLARKE: Turning your attention, if I can, to page 9 of your CV, in particular a publication numbered 89 entitled, "Effects of inbreeding on forensic calculations," was that another paper that you personally authored?
DR. WEIR: Yes, it is one of my more recent and we always think our most recent papers are our best, but this was an invited paper for the annual review of genetics. The invitation came some time ago and then when it came time to actually put pen to paper, I chose to write on this current area of the forensic applications. The paper was invited, but it still was subject to a peer review, and although it has a somewhat narrow focus, I really took the opportunity to summarize a great deal of my thinking in the appropriate ways of analyzing the data. And I think I should say here that--that this, I believe, lays out the appropriate way to account for population structuring and thereby diffuse some of the problems people have felt faced by these data.
MR. CLARKE: Turning to the next page, page 10, there is also a category labeled "Commentaries and correspondence."
DR. WEIR: Yes, uh-huh.
MR. CLARKE: That appears to have thirteen different items it in. Can you just tell us in summary fashion what commentaries and correspondence are?
DR. WEIR: Well, I would like to remove from my publication those things which are not scientific papers in the sense of being through a peer review process and present novel scientific information. Some of these are reviews. The 1992 paper and the proceedings of the national academy of science was a review of the population genetic issues. I was invited by the editor of the journal to write a review, which I was pleased to do, but it did not go through a review process, a formal review. I solicited comments from several colleagues, so that is a review, then there are several letters which are felt are sufficiently annoyed with papers and journals that I would write a response, particularly to science and nature who have published once again non-peer reviewed--I don't want to say articles because they are not article--pieces of writing, they have published items often critical of the forensic uses of DNA. I think they have given a very one-sided view of the debate and occasion I have managed to get a rebuttal letter published.
MR. CLARKE: When you are referring to science and nature you are referring to science magazine and nature magazine?
DR. WEIR: Yes, sir.
MR. CLARKE: Turning to page 11, in particular a category labeled "Books," have you published books in the area of population genetics and their relationship with statistical data?
DR. WEIR: Yes. In 1990 I published a book genetic data analysis which is meant to be a very broad reference work, if would you like, of all the methods likely to be encountered by people generating genetic data of the kind we will be talking about and some other kinds. In press currently there is a book to be published by a kluwer entitled human identification. For that volume I acted as editor. I solicited articles from a variety of people who have made substantial contributions to this field and I was pleased with. They agreed to write papers. The articles all went through a review process. The collection of papers has appeared already as a special issue of a Journal Genetica and will appear as a hard cover book later this year.
MR. CLARKE: When you use the word kluwer, is that K-L-U-W-E-R?
DR. WEIR: Yes, sir.
MR. CLARKE: Turning if we can to what appears to be a second page 11; is that right?
DR. WEIR: Probably it does appear to be that way. It should be page 12, I'm sorry.
MR. CLARKE: There is also a category entitled "Book reviews"; is that right?
DR. WEIR: This is of very little consequence, I think. I publish reviews of other people's books.
MR. CLARKE: In the same general area as you have described earlier?
DR. WEIR: Generally population genetics and statistics.
MR. CLARKE: Then lastly, on what appearing to be the remaining two pages, there is a listing of published abstracts by you?
DR. WEIR: Yes.
MR. CLARKE: Briefly, what are those?
DR. WEIR: These are just descriptions of presentations of some meetings.
MR. CLARKE: All right. Your Honor, for purposes of this hearing I would ask that this particular exhibit, People's exhibit 407, be admitted.
MR. THOMPSON: No objection.
THE COURT: All right. It will be admitted.
(Peo's 407 = in evid)
MR. CLARKE: Dr. Weir, I would like to turn your attention to any activity you may have in terms of consulting forensic DNA cases.
DR. WEIR: Yes.
MR. CLARKE: First of all, do you engage in that type of activity?
DR. WEIR: Yes, I do.
MR. CLARKE: What type of role do you have when you do that?
DR. WEIR: Well, on cases in particular I'm approached by both Defense and Prosecution attorneys to give them assistance. I've al declined Defense requests because I don't believe I can argue against the forensic uses of DNA, so when an attorney contacts me for the Prosecution, I ask to see a copy of all reports provided them by the forensic scientists, and I focus on the statistical aspects of those reports. I then obtain the necessary databases used by that particular forensic scientist, conduct tests of such things as association. Essentially duplicate the statistical aspects of the report and then, if necessary, I give testimony at both admissibility hearings and the subsequent trial.
MR. CLARKE: Now, when you say you review the data, do you review the data in terms of not only the results of DNA testing in a forensic case, but also ultimately what are the frequencies reported to describe any matches?
DR. WEIR: Oh, yes, that is part of my analysis.
MR. CLARKE: And as far as looking at that type of data and your analysis, what are you looking for?
DR. WEIR: I'm looking for confirmation of my prior beliefs that the DNA markers used in forensic science associated freely, there is no evidence for dependence within loci.
MR. CLARKE: Does that again relate to the ultimate use in a given case?
DR. WEIR: Yes, I'm sorry. Once we have demonstrated consistency with independence, then we may proceed to use the product rule. As I think I said earlier, if I find evidence for dependence, then we have to modify the production of profile frequencies.
MR. CLARKE: When you use the term "Dependence," would that then be the same as referring to association, if you find it?
DR. WEIR: That's right.
MR. CLARKE: Approximately how many times have you consulted in this manner you've described?
DR. WEIR: I think I've given testimony in sixteen cases.
MR. CLARKE: And is that in one state or more than one state of this country?
DR. WEIR: It is--east and west coasts, California, Oregon, Washington on the west coast.
MR. CLARKE: And in those instances have you been allowed to testify as an expert in this area of genetic data and population frequencies?
DR. WEIR: Yes.
MR. CLARKE: Now, as far as your own experience, and if you could describe to the Court, please, how is it that in terms of these DNA type techniques and genetic marker results that are obtained using them, that you became involved and experienced in examining the data obtained as a result of these testings? Is that question clear?
DR. WEIR: It wasn't particularly clear.
MR. CLARKE: I didn't think so. What I'm really asking you, Dr. Weir, is, as far as these DNA typing techniques and then ultimately obtaining results from them, how did you gain your experience to be able to look at these results and then determine from these tests whether or not there is, for instance, any of this association?
DR. WEIR: Well, my experience really points to my entire career since my--the early publications I have been involved in setting up methods, not all of them of course directly relevant, but we talked about a 1979 paper. And at that time we were setting up statistical methods to analyze genetic data. This was, remember, a long time before DNA markers were in vogue. The methods we developed at that point have--have come to be seen as appropriate for the data we are currently involved with. So I think I'm qualified and have been requested to work on these issues on the basis of my publications, which as I said, date back a long way.
MR. CLARKE: And they deal with, for example, RFLP typing results and data generated as a result of that?
DR. WEIR: Oh, certainly.
MR. CLARKE: As well as PCR type results?
DR. WEIR: Absolutely.
MR. CLARKE: Have you in fact developed methods, that is, personally developed methods to evaluate this type of information?
DR. WEIR: Well, I can't publish a paper unless I have something new, so my papers I think invariably describe new tests or new approaches to old tests or evaluations of tests, so I think it is fair to say that the methods I use are either so standard that they don't need to be justified or they are ones that we have worked on provided the justification.
MR. CLARKE: You described around I believe it was 1983 during your sabbatical and I think that was the Guggenheim fellowship period?
DR. WEIR: Yes, sir.
MR. CLARKE: That obviously--or first of all, let me ask it as a question. Was that around the time that DNA typing techniques were being developed?
DR. WEIR: As it turns out probably while I was sitting in Edinburgh Professor Jeffries was down the road at Lester working on the method which subsequently came to be called DNA fingerprints.
MR. CLARKE: As far as these methods that you utilized or have developed to evaluate genetic marker data, did you develop some of those methods even before DNA typing was available?
DR. WEIR: Yes, certainly.
MR. CLARKE: And have you developed additional methods since DNA typing has been available?
DR. WEIR: Yes. One of the--one of the interesting aspects of the forensic uses, apart from the obvious applications, the interest to me is that the data are so discriminating, the RFLPs in particular have so many types, which is the reason they are used, that they presented some novel challenges for such issues as testing for independence, so we had to do a little development and extension of our previous works and then of course our methods must be tailored to the way that the data are generated. I'm sure you've heard described Cellmark's floating bands method or the FBI's fixed band method. These are different ways of generating data. Those different ways must be reflected in the method of analysis, so I've had to accommodate those methods in the subsequent analyses.
MR. CLARKE: That was actually going to be the next question I asked and perhaps I can ask it in a somewhat summary fashion: In your evaluation of DNA typing data, do you use methods that were involved either by yourself or others even before DNA typing was available?
DR. WEIR: Yes. I think I've said that, yes.
MR. CLARKE: And do you also then use methods developed either by yourself or others to evaluate DNA typing data that were involved as DNA typing was available?
DR. WEIR: Certainly, yes. I think it is necessary to perform appropriate statistical validation studies on the forensic databases--
MR. CLARKE: So is it correct--I'm sorry.
DR. WEIR: --before they are used.
MR. CLARKE: Is it correct to say then that many of these techniques that are even used today to evaluate DNA data have been in existence for many, many years?
DR. WEIR: Oh, certainly.
MR. CLARKE: Now I would like to turn your attention, Dr. Weir, to experience that you've previously had with Cellmark diagnostics.
DR. WEIR: All right.
MR. CLARKE: Is there any relationship between your university and Cellmark?
DR. WEIR: Yes. We have a contractual arrangement. I think it is effectively called a memorandum of understanding whereby my university undertakes to perform analyses for Cellmark.
MR. CLARKE: What work do you--well, first of all, are you involved in that relationship?
DR. WEIR: Yes.
MR. CLARKE: What type of work does that entail?
DR. WEIR: I'm currently--the immediate reason for the contract was to evaluate their new databases. As you probably know, they have data collected from their paternity testing business, and they have culled data from their paternity records to serve as a forensic database and Cellmark wished these new databases to be evaluated for independence.
MR. CLARKE: And you have been involved in that evaluation?
DR. WEIR: Yes, sir.
MR. CLARKE: Are you familiar with the methods used in Cellmark or at Cellmark diagnostics as far as reporting population frequency data based on DNA matches?
DR. WEIR: Yes, I am.
MR. CLARKE: When did you first become familiar with the methods that they utilize?
DR. WEIR: I think it must have been late 1990. I had discussions with them and they provided me with copies of their then current databases and were very generous in both sharing the data and explaining in some detail how the data were collected, how they were used, explained their banding strategies and so forth. And with their cooperation I was able to perform analyses and subsequently publish those, I think it was 1990 in the paper in the American Journal of Human Genetics.
MR. CLARKE: In fact in your CV do you list a specific reference, and perhaps if you are able to point us in the direction of what publication number that publication is in which you published your own results of evaluating data at Cellmark?
DR. WEIR: That is item no. 77. It was published in 1992.
MR. CLARKE: Listed on page 8 of your CV?
DR. WEIR: Yes, sir.
MR. CLARKE: I'm sorry, that was no. 77?
DR. WEIR: No. 77.
MR. CLARKE: As far as your familiarity with frequency calculations and frequency data as Cellmark, does that include RFLP data?
DR. WEIR: Yes. This--this paper we are talking about here was RFLP. As part of our contract we've also examined their current PCR database.
MR. CLARKE: Would that include the genetic marker DQ-Alpha?
DR. WEIR: DQ-Alpha polymarker, yes.
MR. CLARKE: When you use the term "Polymarker" are you referring to five individual genetic markers that are collectively referred to as polymarker or PM?
DR. WEIR: That's right.
MR. CLARKE: I would like to turn your attention, Dr. Weir, to the California Department of Justice.
DR. WEIR: All right.
MR. CLARKE: To your knowledge--well, first of all, are you aware of what types of data are used at the California Department of Justice in the area of frequency data?
DR. WEIR: Yes. Over the last few months I have held--I had several conversations with a Gary Sims who explained to me that Cellmark--excuse me--the DOJ uses data collected by the FBI.
MR. CLARKE: Could you describe for the Court, please, how and if you are familiar with FBI data in the area of DNA typing?
DR. WEIR: Yes. I first met Dr. Budowle from the FBI I think in December of 1989 and he asked for some assistance in collaboration on interpreting and analyzing their databases and subsequently provided me with their current and subsequent versions of their various databases. As a result of that initial contact I did some work on their RFLPs and published an analysis of that also in 1992, item no. 72, a paper published in the journal of genetics. Since this time I've kept close contact with the FBI and we have no financial contractual arrangements at all with the FBI. I've kept close contact with them and they have added more probes. I have kept up, if you like, with their analysis, and the most recent data I obtained from them was in this year, RFLP, and I've also got a copy of their--a set of their PCR-based loci and performed analyses on those.
MR. CLARKE: So you are familiar with the FBI's databases as used by the Department of Justice in this case both in the "A" markers as well as the PCR markers used at the Department of Justice?
DR. WEIR: Yes, I am.
MR. CLARKE: To your knowledge does that include DQ-Alpha and D1S80, and I'm referring to the Department of Justice?
DR. WEIR: Yes. There is a compilation of seven loci; DQ-Alpha, D1S80 and the five collectively known as the polymarker.
MR. CLARKE: The publication you described, that publication involved your analysis of FBI data; is that right, in particular, RFLP frequencies?
DR. WEIR: Item no. 72 and then a more recent paper, the one, no. 96, also an RFLP data from the FBI.
MR. CLARKE: And that was published in the journal of genetics?
DR. WEIR: Genetica.
MR. CLARKE: As far as your own personal analysis of data, has that been limited to Cellmark and the FBI or has it included other forensic laboratories?
DR. WEIR: No. I've been kept quite busy in the private sector. I've looked at data from lifecodes, genetic design and a Roche Biomedical. In the government agencies, apart from the FBI, the State Bureau of Investigation in North Carolina and the corresponding agencies in South Carolina, Dade County and Broward County in Florida, Minnesota, Oregon, Toronto, New Zealand, Australia and United Kingdom.
MR. CLARKE: Now, in these analyses that you undertake with regard to these labs, can you briefly tell us what that entails? What are you looking for?
DR. WEIR: Well, we are looking primarily for any evidence of associations between the various types and we are also looking for measures to the degree to which different populations differ; the amount of difference and frequencies between, say, Caucasians and Hispanics.
MR. CLARKE: Have you, first of all, with reference to this particular case before the Court involving Mr. Simpson, have you undertaken a review of frequency data generated by both Cellmark and the California Department of Justice?
DR. WEIR: Yes.
MR. CLARKE: And in the course of that review have you produced a report?
DR. WEIR: I have a somewhat fluid report, yes.
MR. CLARKE: By "Fluid" what do you mean?
DR. WEIR: I mean it has been undergoing improvements.
MR. CLARKE: Your Honor, at this time I would ask to have marked as--perhaps the best method would be exhibit 408--
THE COURT: All right.
MR. CLARKE: --and 408-A, and I will describe them. Exhibit 408-A appears to be a report by Dr. Weir dated June 21st, 1995, consisting of what appear to be one cover sheet plus pages 1 through 48. And I would ask that 408-B, a similar report dated also June 21st, but with the additional notations "Addendum" which appears to consist of four pages plus a cover sheet.
THE COURT: Thank you.
(Peo's 408 for ID = Dr. Weir report)
(Peo's 408-A for ID = Dr. Weir report/addendum)
MR. CLARKE: Which have been provided to the Defense at more than one time period in different forms.
MR. CLARKE: Dr. Weir, showing first what will be exhibit 408, the lengthier document, is that the report that you have prepared in this case?
DR. WEIR: Yes, it is.
MR. CLARKE: Referring specifically--well, let me go a little further with exhibit 408. First of all, that has some stamped number in the upper right-hand corner; is that right?
DR. WEIR: DNA, is it, 09477.
MR. CLARKE: You are not involved in the placement of those numbers; is that right?
DR. WEIR: No. Those numbers are not mine.
MR. CLARKE: With regard to this particular document--and it is dated yesterday; is that right, June 21st?
DR. WEIR: Yes.
MR. CLARKE: Did you, since yesterday, produce what can be categorized as two replacement pages with some changes in data on two of the pages?
DR. WEIR: Yes, I did, and I should apologize, although I don't think I am completely to blame, in doing PCR--in doing RFLP calculations for the DOJ report, I had included all the bands they reported in their profiles, forgetting or not knowing that they do not report frequencies on the high molecular weight bands, so that I apologize for that. I removed those bands yesterday and essentially replaced those two pages.
MR. CLARKE: That led to a correction of those two pages?
DR. WEIR: Right.
MR. CLARKE: In other words, the information you obtained yesterday?
DR. WEIR: Yes.
MR. CLARKE: Could you just tell us what your page numbers are for those two pages so that the record will be clear?
DR. WEIR: It is pages 21--excuse me. Page 22 and the corrections are on table 18, and I see this copy is annotated, replaces, and then on page--I believe it is page 43.
MR. CLARKE: Or 41?
DR. WEIR: Excuse me. Table 41, table 32. Those are both tables, refers to the DOJ's RFLP calculations now reflecting the fact that the high molecular weight bands do not have frequencies assigned to them.
MR. CLARKE: Incidentally, do those corrections in those two replacement pages have anything to do with DNA mixtures in this case?
DR. WEIR: Oh, no, no.
MR. CLARKE: Now, if I can turn your attention to the shorter document, 408-A, can you simply tell us briefly what this document is.
DR. WEIR: Yes. The--my full report contains information on mixtures, except for the RFLP mixtures on the glove reported by DOJ. I received that information later, so this addendum is simply to present really a table of frequencies for the three items from the glove on which there were RFLP mixtures.
MR. CLARKE: So the addendum 408-A refers to RFLP glove mixtures; is that right?
DR. WEIR: Yes, sir.
MR. CLARKE: Now--
DR. WEIR: From DOJ.
MR. CLARKE: From the Department of Justice?
DR. WEIR: Yes.
MR. CLARKE: As far as this case, can you describe for us the material that you reviewed to conduct your analysis?
DR. WEIR: Well, I've reviewed the various reports provided by both Cellmark and DOJ and of course as always in any such case I review the appropriate databases from either the FBI or from Cellmark. Maybe this is the appropriate place to say that all my calculations rely on three sets of data; the Cellmark, RFLP databases, both their original and any new information. That is one set. The FBI's RFLP data, seven RFLP loci and then the FBI's PCR database, the whole seven PCR loci.
MR. CLARKE: As far as this review, you utilized material provided to you by both laboratories?
DR. WEIR: Well, I--yes, both their reports, which I obtained through the Prosecution and numerous telephone conversations.
MR. CLARKE: That was actually going to be my next question. Did there come instances or did there arise instances in which you had questions that you needed answers from the testing laboratories?
DR. WEIR: Yes. And in particular on the mixtures. I needed to be absolutely sure what the--what the labs had found in their mixture studies and I believe I now understand that and they greatly simplified the analysis to have a complete understanding.
MR. CLARKE: Did there come a time when you were asked to--you were requested to examine pictures in this case as far as frequency data was concerned?
DR. WEIR: Well, I'm not sure. As soon as I obtained the reports, I proceeded to do an analysis and then I think Miss Kahn asked me, or maybe it was you, who asked me a little while ago to do a complete analysis.
MR. CLARKE: Perhaps we can provide a little bit of a history. Did you produce an initial report earlier this year?
DR. WEIR: Well, yes. In December I wrote a report and began on the analysis of mixtures and didn't proceed very far at that point, merely to point out that there were mixtures available, these needed to be interpreted, but I don't believe I did any calculations at that point.
MR. CLARKE: Did you perform calculations on the non-mixtures?
DR. WEIR: Oh, yes, on all single stains that were available to me then.
MR. CLARKE: And I believe you said that was as early as December?
DR. WEIR: Yes. I wrote the report and sent it late December.
MR. CLARKE: Now, carrying forward to later in 1995 were you at some point asked to look at mixtures in terms of calculating frequencies?
DR. WEIR: Yes.
MR. CLARKE: And you simply don't recall if that was Miss Kahn or myself?
DR. WEIR: No, I don't.
MR. CLARKE: Can I have just a moment, your Honor?
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: Dr. Weir, as far as mixtures, what I'm going to ask you to do is describe for the Court, please, about the area of attaching frequencies to mixtures. What can you tell us about that?
DR. WEIR: Well, I would like to do it slowly.
MR. CLARKE: That is a good idea.
DR. WEIR: To set the language to talk about single stains first because it is not different. When there is a single stain found to match a person of interest, to attach some numerical weight to that evidence of a match, the first step is to calculate the frequency with which random people would produce the profile found in the stain. So we loosely say we calculate the frequency of the--of the evidentiary profile. In essence we add up all the possible people who could have contributed. Now, the addition is kind of trivial because there is only one type, this is a single genotype, and we add up that single genotype frequency. And that number is what we've seen reported in this case. Typically these are given as 1 in some number, 1 in a thousand, 1 in a million. Remember that those are frequencies. Frequencies of the stain. It is best to interpret that number by flipping it upside down and saying the evidence is a thousand times more likely to have arisen if it was given by this person versus if it was given by an unknown person. It is the unknown person for whom we've calculated the frequency. Now let's turn to a mixture and if we look at the--all the typing, and there are more than two alleles at any locus--
MR. CLARKE: And you are referring now to whether it is RFLP or PCR markers?
DR. WEIR: That's correct. Any of the loci examined, if they have more than two alleles, we have evidence that there was more than one contributor to the stain. If we look at all the loci and found two, three or four alleles at every locus, we have evidence that there were two contributors. If we found more than four alleles at any locus, we would have evidence of at least three contributors, and so forth. To keep things in focus here, let's suppose that the evidence and all the loci typed has four or fewer alleles. The evidence points to their being two contributors. We want to attach a frequency. The question--and it is not possible to avoid the proper framework. The framework is how do we interpret the evidence. We believe either that the evidence, the stain, was contributed by these two particular people or three particular people or it was not. The "Or it was not" can be interpreted as this stain was contributed by two unknown people or by three unknown people. What is the frequency with which two unknown people would contribute this stain? So we add up all the frequencies of two people, pairs of people, who between them would have this mixed stain. So if there was a single locus and there were four bands, four alleles, 1, 2, 3 and 4, we have to add up all the possibilities. How likely is it that two people, two unknown people between them would have these four bands? The people might be--the first person might have bands 1 and 2 and the second person have bands 3 or 4 or it might be that the first person has bands 1 and 3, second person 2 and 4.
There are a whole host of situations. It is essential to interpret the data correctly. The evidence suggests there is a mixture. To form an analysis which ignores the evidence of there being a mixture is wrong, it is completing misleading. We must add up the frequencies under the situation suggested by the evidence. The evidence suggests two contributors. We must add up the frequencies with which two contributors between them have this mixed profile.
MR. CLARKE: All right. Could I have just a moment again, your Honor?
THE COURT: Yes.
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: Your Honor, at this point I was going to turn to the use of the elmo so that the witness could demonstrate something, however, we apparently need, if we could have, a brief recess to be able to do that.
THE COURT: How brief?
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: Approximately 10 minutes I'm told.
THE COURT: What do we need to have?
MR. CLARKE: Just the overhead projector, the elmo system turned on, because the document is not complicated--using the document is not complicated.
THE COURT: Why don't you just hand me the document.
MR. CLARKE: All right. That's fine. I have given a copy to counsel.
THE COURT: All right.
MR. CLARKE: Actually, let me start with using one of the boards, if I may, your Honor.
THE COURT: All right.
MR. CLARKE: Dr. Weir, what I'm going to ask you to look at is a particular result in this case. First of all--
THE COURT: Mr. Clarke, why don't you go ahead and spin that around, so both the doctor and I can see it, since we don't have to worry about whether the jury can see it. Thank you.
MR. CLARKE: First of all, Dr. Weir, have you seen a smaller or eight-and-a-half-by-eleven version of this particular board?
DR. WEIR: Yes, sir.
MR. CLARKE: What I'm going to ask you to do--and first of all, in your analysis of the results in this case, did you look at what is labeled on this board as item no. 29, steering wheel?
DR. WEIR: Yes.
MR. CLARKE: Would that be an example that you could use, that is, the actual results with regard to that item, to talk about frequencies in mixtures?
DR. WEIR: That would be fine.
MR. CLARKE: That particular item contained results, and let's look, if we can, at simply the DQ-Alpha marker. Is that acceptable?
DR. WEIR: That's fine.
MR. CLARKE: The particular results on item no. 29 at the DQ-Alpha marker showed the appearance of three different alleles; is that right?
DR. WEIR: That's right. And just reading from the board here would be 1.1, 1.2 and 4, and I should say now that I am taking no notice of descriptors such as weaker or possible trace. I am assuming that if the allele is mentioned, it is present.
MR. CLARKE: So when you perform your own analyses, when a particular allele is described as present, you are not paying attention, for frequency purposes, of a description such as weaker, trace, et cetera?
DR. WEIR: That's right.
MR. CLARKE: Now, with regard to that particular item at the DQ-Alpha marker, does that indicate a mixture?
DR. WEIR: Yes. There are three alleles and that must obviously--implies more than one contributor. One person would only have two alleles.
MR. CLARKE: As far as your review of this particular case and the specific results, and in particular with regard to that item, were you asked to calculate an approximate frequency to describe that mixture and how often one might encounter that mixture?
DR. WEIR: Yes, I was, and to calculate the frequency with which two contributors or three contributors would have between them those three alleles.
MR. CLARKE: All right. Your Honor, if I may, I would like to have marked then as exhibit 409 a one-page document that is labeled at the top "Percentage of population included in LAPD no. 29."
THE COURT: All right.
(Peo's 409 for ID = document)
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: I'm told that if the monitors are turned on, that we can proceed, your Honor.
(Brief pause.)
THE COURT: All right. Dr. Weir, I think this is a "On" button on your monitor there.
DR. WEIR: It seems to be on.
THE COURT: Yes, it is.
DR. WEIR: Thank you.
MR. CLARKE: As a foundation, with what will be marked exhibit 409, the one-page document, have you had an opportunity to look at that document?
DR. WEIR: Yes.
MR. CLARKE: You probably are asking yourself what document is it. Did you have a chance--
DR. WEIR: Yes. You have shown me this page, yes.
MR. CLARKE: And does that page relate to item no. 29 and the particular alleles that were revealed by testing by both Cellmark and the Department of Justice?
DR. WEIR: Yes. It just lays out, without the--all the details, it lays out the method I used to calculate the frequency of two contributors to a mixture.
MR. CLARKE: Very good.
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: Actually let me also hand a copy--first of all, Dr. Weir, there have been copies made.
MR. CLARKE: Showing you this one-page document that will be exhibit 409, is that the document that you had an opportunity to look at?
DR. WEIR: Yes, sir.
MR. CLARKE: And we have an extra copy for the Court also, if you could hand yours--
DR. WEIR: Certainly.
(Brief pause.)
MR. CLARKE: Now, Dr. Weir, could you describe what this particular document shows.
DR. WEIR: Yes. This is just as I said, it is to lay out the possibilities with which two people would contribute to the DQ-Alpha mixed stain. As we've said, the mixed stain has three alleles, and we know therefore it is a mixture. I should say there is no evidence at any of the loci typed on item 29 of there being three contributors; however, for this demonstration we have two--we have--we are working under the assumption there where two contributors and I must stress we must work under the assumption of it being a mixture. By definition there is more than one contributor. So we need to examine the possibilities, how likely is it that two people would have between them these three alleles, so we've listed--you have listed out looks like a dozen or so possibilities. The first person, for example, the first row here, the first person could be a 1.1 homozygote, the second person a 1.2 and 4 heterozygote.
MR. CLARKE: In other words, let me stop you for a moment. That is one possibility when there are two contributors to a mixture, to produce the results that were obtained by these laboratories?
DR. WEIR: That's right. If--if those three people were the contributors to the stain, the stain would look like as it does. The stain would have those three alleles, no more and no less, if those three people were the contributors.
MR. CLARKE: Now, is the remainder of that left-hand column or the two left-hand columns, "First person" and "Second person," simply the remaining possibilities for a two-person mixtures producing those results?
DR. WEIR: Yes. I think there are all the possibilities, all the ways in which two people between them could have those three alleles.
THE COURT: Is the second line a misprint, first person 1.2--
DR. WEIR: It should be a 1.2, 4, yes, your Honor.
MR. CLARKE: I'm afraid I will have to take responsibility for that, your Honor.
MR. CLARKE: Incidentally, this document, it was not prepared by you; is that right, Dr. Weir?
DR. WEIR: That's correct.
MR. CLARKE: Should that one point under the listing of first person simply be deleted so that it would read 1.2, 4?
DR. WEIR: Yes.
MR. CLARKE: Now, in the upper portion, and this is referring simply to the first listing of first person, 1.1, 1.1, and second person, 1.2 and then 4, there are listed two categories of racial groups; is that right?
DR. WEIR: That's right. One--excuse me.
MR. CLARKE: Is this simply one listing of what--and if the chart were complete there would be many more listings?
DR. WEIR: That's right. And in all our calculations, single or mixed stains, when we compute frequencies for unknown people we must recognize that these are really unknown. We know nothing about their ethnicity. We don't know which frequencies to attach, so we go through all the possibilities we have. For example, these two people, the first one may have been African American and the second Caucasian, or vice versa, or the first one may have been African American and the second Hispanic or vice versa, and we could go on. And what I have done in this case is to assume that either of the two people were not of four different ethnicities but have frequencies I've taken from four different databases.
MR. CLARKE: Incidentally, this chart, as is shown now on the overhead projector, is it taken simply from your report?
DR. WEIR: This is essentially an extraction of table 29-B.
MR. CLARKE: And in your report have you described all of these combinations under the first person and second person, as well as all of the major racial category combinations for both a two-person and a three-person mixture?
DR. WEIR: I have.
MR. CLARKE: Can you describe for the Court, please, and I'm referring now to again simply the first possible combination listed at the top, how a calculation is made by you or was made by you with regard to this mixture?
DR. WEIR: Yes. We'll I'm invoking the product rule. I'm calculating the frequency of a combination of alleles by multiplying together their separate frequencies.
MR. CLARKE: So if you could, just describe for us what those numbers--what are they describing that are listed under the two racial categories and then ultimately the frequency at the end.
DR. WEIR: All right. So the first line of the table is where the first person was a 1.1 homozygote, this unknown person, and this unknown person has frequencies which could be described by the African American database. Now, I've reported those frequencies in my report, but I will just tell you the frequency in the FBI's PCR database for allele 1.1 in the African Americans is .117, so we square that frequency, multiply it by itself because we have two copies of that allele for that unknown homozygous person.
MR. CLARKE: Let me stop you for a moment. When you square it or multiply it by itself, is that the same process that is used for describing stains from one donor in this case?
DR. WEIR: Certainly.
MR. CLARKE: And that is used across the various boards, is it?
DR. WEIR: Yes.
MR. CLARKE: That you have been provided copies of?
DR. WEIR: Yes.
MR. CLARKE: In other words, those are frequencies that have already, to your knowledge, been reported in Court in this case?
DR. WEIR: Those are the single-person frequencies, yes.
MR. CLARKE: All right. Proceed, if you would.
DR. WEIR: So that we have accounted--now, we have attached a number to the chance of the first person being of 1.1 homozygous genotype and frequency from African American. The second person we have assumed for this calculation are Caucasian. We don't know, we have assumed it for this calculation here, that person is a 1.2, 4 heterozygote, so we multiply together the frequencies of the 1.2 allele. That number is .176 and the 4 allele, that number is .328 and of course we have to double that product from the--we don't know which way round the alleles came to the person, what their parental origins are, so we now have a frequency to--if this is the 2 PQ frequency for that genotype from a Caucasian database.
MR. CLARKE: And again, is that the same step, that is, of multiplying the frequencies of the two different alleles and then multiplying it by two, that is used in the reporting of single-stain DNA results?
DR. WEIR: Yes, it certainly is. Now, because what--now, the only novel feature of this analysis is to recognize there were two contributors and these people, we are assuming, are independent and we multiply their frequencies together, so--and that is the right-hand column, that .00158, which is about .15 percent. That is the frequency with which two people at random have those two specific genotypes, one person being African American and the other being Caucasian.
MR. CLARKE: Now, do you then undertake that same analysis with regard to--and let's just stay with, for the moment, the first possible combination of 1.1, 1.1 and 1.2, 4, do you calculate that for each of the racial combinations that are possible?
DR. WEIR: Yes. As I said, I'm using the FBI's four databases, so there are a total of ten possible pairs of databases.
MR. CLARKE: Do you also then, and did you, in terms of your analysis in this case, perform the same calculation for the remaining eleven combinations of DQ-Alpha types amongst two people?
DR. WEIR: That's right.
MR. CLARKE: And do you, for each one of those, produce ultimately a frequency for each combination that would on this chart, if it were totally complete, then go under the category or column of "Frequency"?
DR. WEIR: That's right.
MR. CLARKE: Once you've done that for each possible combination, what do you do next?
DR. WEIR: Add up those--sum those frequencies, sum the frequencies of the unknown contributors.
MR. CLARKE: In other words, sum in this instance what would be .15 percent, sum the next calculation for the second combination of markers and on down to the bottom with all twelve?
DR. WEIR: That's right. We sum the frequencies of all the possible genotypes for the pairs of people that could have contributed, yes.
MR. CLARKE: And in terms of your analysis in this case, as well as your report, did you report those totals for each racial category combination?
DR. WEIR: Almost. We are almost there. This is for the DQ-Alpha.
MR. CLARKE: Yes.
DR. WEIR: We then need to repeat the calculations for the other loci in the mixture. In this case--well, I guess it is only DQ-Alpha here, so excuse me, so then we are complete. The sum of those twelve numbers as reported here is 1 in 71.
MR. CLARKE: And that would be for what racial category?
DR. WEIR: That is when either of the contributors was African American and the other was Caucasian.
MR. CLARKE: Incidentally, with regard to item 29--and let's clarify that. Assuming that were indeed--well, first of all, were you informed and provided material that there were also polymarker results on the steering wheel?
DR. WEIR: Yes, and I just misled you. The 1 in 71 is in fact the number from using all the loci, so that would be the Cellmark determination. DQ-Alpha plus polymarker I have used all the six loci, done a calculation like we see on this chart, multiplied those results from each locus together, multiplied the sum for each locus.
MR. CLARKE: Now, when you have used the example of 1 out of 71, that was just one of the combinations possible? That is one African American and one Caucasian, correct?
DR. WEIR: Right.
MR. CLARKE: And you also performed this summing technique for each of the combinations of African American, causation, southwest Hispanic and southeast Hispanic?
DR. WEIR: Yes, the whole ten combinations.
MR. CLARKE: And you in fact produced tables showing what the frequencies would be using this calculation method for each of these combinations?
DR. WEIR: I did.
MR. CLARKE: This method that you have described, in your opinion, is that an appropriate one to describe a frequency?
DR. WEIR: It is--it is both my opinion and it is the recommendation from the literature.
MR. CLARKE: When you say "The literature," what are you referring to?
DR. WEIR: I'm referring to a paper by Ian Evett in 1989, I think.
MR. CLARKE: Is that--
DR. WEIR: Evett, 1991 journal of the forensic science society, volume 31, page 41.
THE COURT: Spell the name for--
DR. WEIR: E-v-e-t-t.
MR. CLARKE: What is there about there--well, let me rephrase that question. Did you conduct this same analysis in this same method with regard to the remaining mixtures in this case?
DR. WEIR: Yes, I did.
MR. CLARKE: Does this method apply to RFLP results as well as DQ-Alpha results?
DR. WEIR: Certainly.
MR. CLARKE: I'm sorry. Does it apply to not only RFLP results but also PCR results as well?
DR. WEIR: Yes.
MR. CLARKE: Your Honor, at this time I would ask to be marked as exhibit 410--
THE COURT: 410.
MR. CLARKE: --a document previously provided to the Prosecution by the Defense some weeks ago entitled "Percentage of population included in stain no. 29 Bronco steering wheel." That has a different appearance than the previous chart.
THE COURT: All right.
(Peo's 410 for ID = document)
MR. CLARKE: And perhaps if we could, with the Court's permission, use the projector again.
MR. CLARKE: Dr. Weir, do you see the document that will be marked shortly exhibit 410?
DR. WEIR: Yes.
MR. CLARKE: Have you seen that document previously?
DR. WEIR: Yes.
MR. CLARKE: Does this document refer to the same results, and I'm referring to just the DQ-Alpha results on the same evidence item, no. 29, the steering wheel stain?
DR. WEIR: Yes, it does.
MR. CLARKE: Is this--well, first of all, is this a table of some sort?
DR. WEIR: Yes.
MR. CLARKE: Does it describe--
DR. WEIR: It describes--it adds up--it describes the single-person genotypes who could have been contributors to the stain. Let me restate. It lays out all the genotypes of individual people who could be amongst the contributors to the mixed stain.
MR. CLARKE: How does this compare--and I'm only referring to the listing of possible genotypes. What differences, if any, are there between this chart and your own?
DR. WEIR: Well, they are the same for each--for an individual. That chart and yours both list all the possible genotypes.
MR. CLARKE: There were twelve combinations listed on your chart and there appear to be simply six listings under the term "Matching genotypes" on this second chart exhibit 410; is that right?
DR. WEIR: That's correct.
MR. CLARKE: What is the difference between the two?
DR. WEIR: Well, the one we are looking at on display now is for single people. It has no relevance, of course, because we know this is a mixture. This is a mixture of at least two people. So to add up the frequencies of single individuals I would say at best is misleading.
MR. CLARKE: Well, let's go into a little bit more detail about this chart. What does it list off to the right of the column matching genotypes?
DR. WEIR: Well, for each of the single genotypes the frequencies are listed from three databases and those frequencies I'm sure are correct, so 1.9 percent of Caucasians are expected to be 1.1 DQ-Alpha homozygote. And it is interesting, 1.9 percent, I imagine, if we--I should say we have slightly different databases, but that 1.9 corresponds to our previous .117 squared. It is the same--purports to be the same frequency. The numbers are different because they are different databases.
MR. CLARKE: Okay. Let me stop you for just a moment. As far as a description of differences in approaches to mixtures, the fact that the databases in this specific example are different, does that impact your ability to describe the different approaches to--
DR. WEIR: No.
MR. CLARKE: --frequency calculations?
DR. WEIR: No, it has no impact.
MR. CLARKE: Now, as far as these frequencies then on this chart, exhibit 410, do they reflect then simply frequencies in these three racial groups, major racial groups of these different six genotypes?
DR. WEIR: That's right.
MR. CLARKE: You have used the term "This is misleading" referring to this chart; is that right?
DR. WEIR: Absolutely is, yes.
MR. CLARKE: And you are referring to it being misleading in the context of the results for item 29 in this case; is that right?
DR. WEIR: Yes, I believe it is quite misleading.
MR. CLARKE: Why is it quite misleading?
DR. WEIR: Because it gives the impression that this mixed genotype would occur--it gives the impression--it doesn't say so, but it gives the impression that this mixed stain would occur in 45.4 percent of Caucasians. Now, I know that is not what that chart says, but that is the distinct impression it is giving. The impression is given that this mixed stain would be found almost half the time if the unknown contributor was Caucasian. That is nonsense.
MR. CLARKE: Why?
DR. WEIR: Because we have a mixture of three alleles from two people or more. It is not--it makes no sense at all to say that that mixture could occur nearly fifty percent of the time--
MR. CLARKE: With regard to--I'm sorry.
DR. WEIR: --when I have just demonstrated that the frequency with which two people would give rise to that mixture is 1 in 71 and we can go on to describe the frequency with three people. We cannot and should not present any analyses on mixtures which ignore the fact that it is a mixture.
MR. CLARKE: In your opinion, does this chart, simply summing up the genotypes, ignore the fact that the stain is a mixture?
DR. WEIR: It does.
MR. CLARKE: In your own calculations--and I believe you have already stated you did it for both two possible contributors as well as three possible contributors; is that right?
DR. WEIR: I did.
MR. CLARKE: Does this calculation process, as shown again in the document, exhibit 410, that is on the projector, does it differentiate in any manner between two contributors, three contributors or however many?
DR. WEIR: This document makes no such distinction. It is only for a single contributor, in fact.
MR. CLARKE: In your opinion, is the method utilized by you in this case a more accurate and reliable means of assigning a frequency to a mixture?
DR. WEIR: I would take out the word "More." It is reliable and accurate.
MR. CLARKE: In your view is the method, as demonstrated by this exhibit, 410, can you say the same about it?
DR. WEIR: It is not appropriate.
MR. CLARKE: Now, for purposes of this hearing only, your Honor, I'm going to ask the witness to refer to a passage that we have previously discussed in the National Research Council report.
THE COURT: Funny. I was about to do that myself.
MR. CLARKE: And I think I have a Xeroxed copy of that page, if that is acceptable. I don't know if the Court wants it marked as an exhibit or not.
THE COURT: We can refer to it as page 59 of the NRC report, if that is what you are about to do.
MR. CLARKE: Yes, exactly.
THE COURT: All right.
MR. CLARKE: Showing you, Dr. Weir, a one-page Xerox--first of all, have you had an opportunity before today to read a document entitled "DNA technology in forensic science" from the National Research Council?
DR. WEIR: Yes, I have read it.
MR. CLARKE: Have you in fact read it in detail on prior occasions?
DR. WEIR: Yes.
MR. CLARKE: The document before you, that is simply a one-page Xerox, although I believe it has some highlighting on it in yellow of in particular page 59 of that report?
DR. WEIR: Yes, it is.
MR. CLARKE: That report contains a reference to samples that are mixtures; is that right?
DR. WEIR: Yes.
MR. CLARKE: And in particular with respect to that reference, the final sentence in what appears to be the fourth full paragraph contains a statement about an appropriate manner, according to this report, of dealing with mixtures; is that right?
DR. WEIR: That's right.
MR. CLARKE: Could you just read that sentence.
DR. WEIR: "If a suspect's pattern is found within the mixed pattern, the appropriate frequency to assign such a match is the sum of the frequencies of all genotypes that are contained within. Ie, that are a sub-set of the mixed pattern."
MR. CLARKE: With regard to that statement, what does that mean to you as an expert?
DR. WEIR: Well, I have trouble answering that question as I would have answering any question on this NRC report, however, because I have little regard for the report's statistics. The report is saying that we should add up the frequencies of all genotypes that is contained. The sentence is ambiguous. It would allow a person to interpret as adding up the genotypes for single people, as we see on the chart--on the board, or to add up the frequencies of genotypes, meaning genotypes of the plural contributors, which is what I've done.
MR. CLARKE: Okay. Let me stop you for just a moment. From your reading of that one-sentence description or recommendation, is it your opinion that it is written in such a fashion that you can't determine from its words whether it is describing the technique that you have used in this case or any other technique?
DR. WEIR: I believe it is ambiguous, yes.
MR. CLARKE: In your view does it cover the technique as shown by exhibit 410, which is simply adding up genotypes?
DR. WEIR: Yes.
MR. CLARKE: In your opinion does it also include the technique utilized by you and previously described this morning in this case?
DR. WEIR: I think it does, but I don't think that is relevant to my calculations.
MR. CLARKE: In what sense?
DR. WEIR: Because I'm not going to base any of my calculations on this NRC report.
MR. CLARKE: As far as multiple contributors, and I may have asked this before, you have done it for two or three possible contributors in this case?
DR. WEIR: That is right. As I said, the evidence contains information of more than one contributor. It contains no information whatever of more than two contributors. I know that there would be interest in there being three contributors to some of the stains. The evidence points to two contributors. I have chosen to do calculations as if there were three contributors in addition.
MR. CLARKE: Your technique allows you the ability to do that for more than two, three, four, et cetera?
DR. WEIR: Certainly. The calculations get more lengthy, but no more complicated.
(Discussion held off the record between the Deputy District Attorneys.)
MR. CLARKE: Your Honor, I would like to move in these three remaining--actually I think it is four remaining exhibits, again for purposes of this hearing only, and I think that would be 408 as well as 408-A, 409 and 410.
MR. THOMPSON: No objection.
THE COURT: All right. They will be received.
(Peo's 408 thru 410 = in evid)
MR. CLARKE: I have no further questions.
THE COURT: All right. Let's take a ten-minute break and we will start with the cross-examination. All right, doctor. You can step down. Thank you.
(Recess.)
(The Defendant not being present.)
THE COURT: Back on the record in the Simpson matter. Mr. Simpson is not present, however counsel, Mr. Scheck, did you wish to address the Court on that issue?
MR. SCHECK: Your Honor, Mr. Simpson has asked me to waive his presence for purposes of the remainder of the hearing so that he can consult with co-counsel and work on other matters.
THE COURT: All right. Presently co-counsel are in the lock-up?
MR. SCHECK: Yes.
THE COURT: Consulting with Mr. Simpson?
MR. SCHECK: Yes.
THE COURT: And you represent to the Court as an Officer of the Court that you have your client's permission to waive his presence for the remainder of this hearing, correct?
MR. SCHECK: Yes.
THE COURT: All right. The Court will accept the waiver. All right. Dr. Weir, would you resume the witness stand, please. All right. Mr. Thompson, you may commence your cross-examination.
MR. THOMPSON: Thank you, your Honor.
CROSS-EXAMINATION BY MR. THOMPSON
MR. THOMPSON: Good morning, Dr. Weir.
DR. WEIR: Good morning.
MR. THOMPSON: Now, the section of the National Research Council report that we are talking about on page 59 has the following language. It says: "If a suspect's pattern is found within the mixed pattern, the appropriate frequency to assign to such a match is the sum of the frequencies of all genotypes that are contained within."
DR. WEIR: Yes.
MR. THOMPSON: Now, can you tell us, Dr. Weir, what is a genotype?
DR. WEIR: Oh, a genotype is a description of the genes or the alleles of an individual.
MR. THOMPSON: Of an individual?
DR. WEIR: Yes.
MR. THOMPSON: Not two individuals?
DR. WEIR: In usual language, yes.
MR. THOMPSON: And the term "Genotype" doesn't refer to the genetic characteristics of three individuals either, does it?
DR. WEIR: Not generally, no.
MR. THOMPSON: No. So the term "Genotype" refers to the genetic characteristics of a single individual; isn't that right?
DR. WEIR: That's right, but of course the language of this report, if we stuck to that, that would make no sense, so I interpret "Genotypes" here to mean genotypes to the contributors of the mixed stain.
MR. THOMPSON: All right.
DR. WEIR: It would make no sense otherwise.
MR. THOMPSON: But that is your interpretation; that is not what the National Research Council says, is it?
DR. WEIR: The National Research Council is reporting mixtures. We couldn't do a mixture analysis ignoring the fact that it is a mixture, so I take this as just loose language.
MR. THOMPSON: Could I have chart 410 placed on the elmo, please.
MR. THOMPSON: Dr. Weir, I would like you to take a look at this chart that has previously been marked chart 410 that has been prepared by the Defense, and I think you will see on this chart there is a list of numbers that are summed.
DR. WEIR: Yes.
MR. THOMPSON: Can you tell me is each of those numbers the frequency of a genotype?
DR. WEIR: Yes, I believe so.
MR. THOMPSON: All right. Now, let's take a look at chart no. 409, please. Now, Dr. Weir, are you looking at chart 409 which was previously prepared by the Prosecution?
DR. WEIR: Yes, I am.
MR. THOMPSON: All right. Now, I would like you to look at this--the number that is listed under the column headed "Frequency," this number .15 percent.
DR. WEIR: Yes.
MR. THOMPSON: Dr. Weir, is that the frequency of a genotype?
DR. WEIR: It is the frequency of genotypes of the contributors to the mixed stain.
MR. THOMPSON: But it is not the frequency of a genotype is it?
DR. WEIR: Certainly not. That would be quite inappropriate.
MR. THOMPSON: And what it actually is, is the product of the frequencies of two genos, isn't it?
DR. WEIR: Certainly, certainly.
MR. THOMPSON: And the reason that that number is so small, that is the .15 percent, is that you have taken two--two numbers and multiplied them together, taken two percentages and multiplied them together to get a smaller percentage? Isn't what you have done?
DR. WEIR: The frequency is the product, yes.
MR. THOMPSON: All right. Now, does the National Research Council report say anything about taking the product of two frequencies before you sum up these--
DR. WEIR: No, no, but that is implied by the language. The frequency of the genotypes couldn't mean anything else.
MR. THOMPSON: So your conclusion is that it couldn't mean anything else? That is the way you read it?
DR. WEIR: Certainly we are talking about a mixture. To talk about an analysis of a mixture ignoring the mixtures would make no sense and I don't believe that that was what was intended.
MR. THOMPSON: Is that what you always believed--
DR. WEIR: The--
MR. THOMPSON: --the NRC report meant or is this a new interpretation you arrived at only recently?
DR. WEIR: I had never thought about this until quite recently. I have always done it the correct way.
MR. THOMPSON: Well, what perplexes me, Dr. Weir, is that you have prepared several different versions of a report in this case.
DR. WEIR: Yes, I have, yes.
MR. CLARKE: Excuse me. Argumentative, the form of the question.
THE COURT: Overruled. Proceed.
MR. THOMPSON: All right.
MR. THOMPSON: We have one report from you that is co-authored with Mr. Buckleton?
DR. WEIR: Dr. Buckleton.
MR. THOMPSON: Dr. Buckleton. That is dated May 11th?
DR. WEIR: Yes.
MR. THOMPSON: And in the report with Dr. Buckleton you use likelihood ratios, a different kind of statistics--
DR. WEIR: No, not a different kind of statistic.
MR. THOMPSON: All right. Let me rephrase the question. You use likelihood ratios to provide a measure to the extent of which the evidence favors one scenario over another; is that correct?
DR. WEIR: The complete analysis must be in that framework. Of course a part of that calculation is the part where we are discussing at this point. This is the first part and in the complete and appropriate analysis.
MR. THOMPSON: All right. And then on May 31st you produced another report labeled a draft. This one single page authored by yourself; is that right?
DR. WEIR: If you say, yes, uh-huh.
MR. THOMPSON: All right. And this report also used likelihood ratios to characterize the value of mixtures?
DR. WEIR: Oh, as does my current report. The phrasing is still there, but my current report is focusing on this component of the likelihood ratio.
MR. THOMPSON: Uh-huh. And in fact the report says likelihood ratios are essential in interpreting the evidentiary value of mixed stains, doesn't it?
DR. WEIR: Yes. That is true, yes, whether that is single or mixed and of course we have had them throughout this case. Every number that is on the board is in fact giving us a likelihood ratio. The numbers I have discussed this morning for the mixture stains are giving us likelihood ratios by inverting them.
MR. THOMPSON: Likelihood ratios for distinguishing between what hypothesis, Dr. Weir?
DR. WEIR: The hypothesis of the two contributors being known versus them both being unknown.
MR. THOMPSON: Okay. Are you planning to tell the jury that those frequency numbers are in fact likelihood ratios?
DR. WEIR: If I am asked and under oath I would have no choice but to say of course they are.
MR. THOMPSON: Okay. Then there was another report that was produced just this week with the date of June 20th. Are you familiar with that? That was June 20th is actually Tuesday.
DR. WEIR: Yes.
MR. THOMPSON: All right.
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: There is a June 20th report. On Tuesday we got a report. This report also used likelihood ratios; is that right?
DR. WEIR: Well, all the reports have likelihood ratio language in them. All the reports also calculate frequencies of multiple contributors to a mixed stain. I'm not sure I understand what the distinction is you are trying to make.
MR. THOMPSON: Okay. And in the report of June 20th you are quite critical of the National Research Council's method for dealing with mixtures, are you not?
DR. WEIR: If it was interpreted as a single mix, yes, a single contributor, I would be, yes.
MR. THOMPSON: Right. In fact, I see the sentence that reads: "In particular the method of assigning frequencies for mixtures suggested by the NRC report ignores the type of the profile of the person or people of interest and therefore has no probative value." Do you remember that sentence being in your report?
DR. WEIR: Yes, but that is a separate issue of course that is talking about the enumerator of the likelihood ratio and that criticism of course is still with us. The--I think we are trying to confuse two issues here. Whether or not we give likelihood ratios is in a sense immaterial, but if we were to, we are comparing frequencies under two scenarios. For example, contributors being known or not known. There are two things. I believe if you merely give the bottom line, you are leaving out the alternative, so regardless of how you calculate the bottom line.
MR. THOMPSON: Right.
DR. WEIR: Yeah.
MR. THOMPSON: Isn't it true, Dr. Weir, that when you were criticizing the National Research Council report in your--in your June 20th report--
DR. WEIR: Yes.
MR. THOMPSON: --you were referring to the interpretation of the National Research Council method for mixtures that has been advocated by the Defense in this hearing?
DR. WEIR: I don't think so. My criticisms are whether or not they--we are comparing frequencies under alternative scenarios.
MR. THOMPSON: All right. And--
(Discussion held off the record between the Deputy District Attorneys.)
MR. THOMPSON: Just one moment, your Honor.
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: Dr. Weir, could you pick up exhibit 408, which is your report of June 21st?
DR. WEIR: Yes, I'm just--I'm just flicking through pages here. Maybe could you help me and refer me to the page.
MR. THOMPSON: If you could direct--direct your attention to page 10.
DR. WEIR: All right.
MR. THOMPSON: The paragraph labeled "Mixed stains." And the--
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: Your Honor, do you have a copy of this?
THE COURT: Yes, I do.
MR. THOMPSON: Okay.
MR. THOMPSON: Now, am I right that the third sentence of that paragraph reads: "Simply adding the frequencies of all possible contributors to the mixture (NRC 1992) Ignores the essential nature of a mixture"?
DR. WEIR: That is what it says, right.
MR. THOMPSON: Now, when you wrote this sentence you were assuming, were you not, that the NRC approach involved simply adding the frequency of all possible contributors to a mixture, weren't you?
DR. WEIR: I think that sentence would--would criticize it if that was the intention. I think, though--
MR. THOMPSON: But isn't it true that--
MR. CLARKE: May the witness finish his answer, please?
THE COURT: Yes.
DR. WEIR: I think, on reflection, I was being unfair to the NRC. I don't believe they would have meant a single contributor. That would have made no sense.
MR. THOMPSON: All right. And so the--the interpretation of the NRC report which is reflected in the report of June 21st is not the interpretation that you now would adopt? Is that what you are saying?
DR. WEIR: We are getting hung up with words here. The correct interpretation of any evidentiary stain is to compare the frequencies and their alternative scenarios. It's simple in a single stain because the likely--the chance that the frequency of the stain under one scenario is just one, it is a hundred percent, so in essence the frequency is hidden from us. And then we calculate the frequency for the unknown and we don't run into any need to examine what we are doing. We can--we can and we have seen the possibility of sloppy thinking, because we have ignored the alternative. For the mixtures we need to consider both alternatives.
MR. THOMPSON: Now--
DR. WEIR: However, one of those alternatives involves multiple unknown contributors and there is only one possible way for calculating the frequency of multiple contributors, regardless of what the NRC said or meant to say or is purported to have said. It is not a question of interpretation. Finally, it is a question of how do you calculate the frequency of multiple contributors, and there is only one way to do that.
MR. THOMPSON: And you are not relying on the NRC report for the basis for your methods in any case, are you?
DR. WEIR: No. Correct.
MR. THOMPSON: You said you were relying on an article published by our friend Ian Evett?
DR. WEIR: That is my published reliance, although I'm relying on my own expertise.
MR. THOMPSON: And when was this article by Dr. Evett and his colleagues published?
DR. WEIR: 1991.
MR. THOMPSON: Wasn't it published in 1990?
DR. WEIR: I thought it was `91. I may be wrong.
MR. THOMPSON: My copy says 1990.
DR. WEIR: I have misspoken.
MR. THOMPSON: I am reading wrong. You are right, so 1991.
MR. THOMPSON: When was the National Research Council published?
DR. WEIR: The report was published in 1990. You have hit on the points. Here is a report which ignores the literature. It is amazing to me that in this and many other instances they have chosen to ignore the correct procedures. Why they didn't cite this paper, I don't know.
MR. THOMPSON: Right. So the very paper on which you were relying was simply ignored by the National Research Council?
DR. WEIR: The paper on which I have cited. I don't rely on that paper.
MR. THOMPSON: All right. All right. Now, this paper by Dr. Evett, the method that it describes is for characterizing mixtures in situations where we know how many contributors there are, is it not?
DR. WEIR: Yes. I think so. That is--well, I believe all the--all our calculations assume a number of contributors, yes.
MR. THOMPSON: Right. Now, but in this case we cannot tell by looking at most of the mixtures how many contributors there are, can we?
DR. WEIR: Oh, I think the evidence is overwhelming that there were two contributors when we have seven RFLP loci and seven PCR loci and I have at most four alleles. I can't imagine any other possible interpretation.
MR. THOMPSON: So does this evidence tell you--can you tell just by looking at the genetic evidence the probability that it is two persons who contributed versus three?
DR. WEIR: I wouldn't attach a probability to that, no.
MR. THOMPSON: You could not attach a probability to it, could you?
DR. WEIR: I'm not sure about that. I would work--yes, I could work out the probability of that event conditional on each of those two assumptions.
MR. THOMPSON: Right. But in order to--in order for you to compute the probability of getting these mixtures, assuming that there are either two people or three people, you would have to make some assumptions about the a priori probability of there being two or three contributors, wouldn't you?
DR. WEIR: No. Well, excuse me. To give a posterior probability of the time analysis, I think the analogy is flawed; however, it ignores what we have been doing throughout the whole trial for a single stain. We compute the frequency of single contributors because all the evidence suggests there is a single contributor. No one has ever suggested we should compute the evidence of a single stain as though there were multiple contributors. All the evidence suggests there are not multiple contributors. I find the argument somewhat vacuous.
MR. THOMPSON: But the answer to the question I just asked you is yes, is it not?
DR. WEIR: You need to rephrase the question.
MR. THOMPSON: Okay. The question is, in order for you to compute the probability of getting these mixtures, assuming there are either two or three people, would you have to make some assumption about the prior probability of there being two or three people?
DR. WEIR: So my answer is certainly no to that. Given--you read that again, you will see that is a conditional probability you have just asked me about.
MR. THOMPSON: All right. Suppose I framed it as a posterior probability. In order to get the posterior probability being two people versus three people--by posterior probability we mean the ultimate issue of there being two or three--we have to make some assumptions about the likelihood there are two or three there initially before we look at the evidence?
DR. WEIR: We are not making posterior probabilities about anything in this trial, single stains or mixture stains or any other issue before us. We have no priors to put in to end up with posteriors.
MR. THOMPSON: When you say the evidence is overwhelmingly in favor of there being two contributors to a stain--
DR. WEIR: Yes, there is. There are seven RFLP loci, each of which has at most four alleles. There are seven PCR loci--well, depending on the stain--each of which has at most four alleles. How could it possibly be three contributors? It is beyond imagination.
MR. THOMPSON: But in order to draw conclusions about the relative likelihood, you have to make some assumptions drawing on other evidence, don't you?
DR. WEIR: The assumption I choose to do these frequencies is that there are either two or three contributors based on the evidence. There are two contributors. I have chosen to do it for three. I could have done it for four. I see no point.
MR. THOMPSON: What about stain no. 29 where we are talking about the stain on the steering wheel?
DR. WEIR: Uh-huh.
MR. THOMPSON: Can you tell by looking at that stain whether there are two or three contributors?
DR. WEIR: I can see no evidence there which suggests three, but you will need to give me some time to look at the RFLPs. They are there. So we have only the PCRs and there are three alleles at all those loci. That is six loci. Excuse me. Six loci have three alleles. There is nothing there which would suggest three contributors.
MR. THOMPSON: Let's assume--let's assume there was no RFLP results on stain no. 29.
DR. WEIR: Well, that is what the chart says.
MR. THOMPSON: All right. And we see alleles.
DR. WEIR: Yes.
MR. THOMPSON: All right. And you say--but you can't determine, based on those three alleles, whether there are two people or three people there, can you?
DR. WEIR: That is--that is a foolish question in the sense that the evidence--
MR. THOMPSON: Will you answer it, please, sir.
THE COURT: Wait, wait, wait, wait. Counsel, he gets to answer the question.
MR. THOMPSON: All right.
DR. WEIR: There are three alleles. We know that each person has two. People may share an allele, so two people may have two alleles, one of which is shared, which would end up with three. I can't imagine why you would invoke three people when there are only three alleles. There may be three people. There may be six people. There is nothing there which would require me to assume more than two.
MR. THOMPSON: All right. And so based on the genetic evidence alone there is no basis for determining whether there is two or three or four?
DR. WEIR: The evidence is that there are only at most four with here only three alleles. The polymarker had four--I think--I would have to look. I think only three alleles. So the evidence says there are three alleles. That means more than one person. It does not say anything about there being three people.
MR. THOMPSON: Uh-huh. And so you can't tell whether there are two versus three based on this evidence alone?
DR. WEIR: I can't tell for certainly.
THE COURT: All right. Mr. Thompson, you have to understand I'm not making this determination in a vacuum. I assume that we have two victims at the crime scene. I'm taking into consideration that there appears to be only one set of footprints. I mean, this is not a determination made in a vacuum. Proceed. Proceed.
MR. THOMPSON: All right. Just one moment.
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: Now, Dr. Weir, the Defense in this case has taken the position that numbers need to be presented to characterize the value of evidence showing consistency between the DNA profile of an individual and a mixed stain. Do you agree that numbers are necessary to show the value of such evidence?
DR. WEIR: My opinion has changed. I think if you had asked me two years ago, I would have agreed. We are now at the point that the numbers are beyond belief. We have got so much genetic evidence, there are so many loci types, some of these items have 11 RFLP loci and 7 PCR loci. There is no number that makes any sense, that is beyond the belief--beyond the experience of anyone to try and interpret. I believe we have passed beyond the point where we should run around trying to make up numbers acceptable to everybody. The evidence of a match at this many loci is compelling, so I think once when we got to the point we are presently at, 7 RFLP loci, 7 PCR loci, the numbers are not necessary.
MR. THOMPSON: What about for evidence like that on item 29? Would the comments you just made apply to that stain as well?
DR. WEIR: Well, my comments apply to seven of each type. On item 29 there are many fewer loci scored.
MR. THOMPSON: Yes.
DR. WEIR: The events of a match is not so astonishing and it is indeed helpful to have a number.
MR. THOMPSON: And so I believe the intention of the Prosecutors initially was to present no number in connection with the mixed stains but merely to present the profile frequencies of individuals who were being compared to the stain. Would you agree with me that that would be a misleading procedure for characterizing the value of stains like no. 29, 305 and the other Bronco stains?
DR. WEIR: Well, that is--I would need to examine each item separately. It would depend on the number of the loci.
MR. THOMPSON: Let's start with no. 29 then. Do you think it would be misleading just to present the individual profile of individuals being compared to the stains, such as Nicole Brown Simpson, and not compute a special number that refers to the likelihood of her matching with the mixtures?
MR. CLARKE: Objection, irrelevant.
THE COURT: Overruled.
DR. WEIR: It is not misleading, no. The evidence remains that there was a match between the evidence and known sample. That is not misleading to say that.
MR. THOMPSON: Well--
DR. WEIR: It is helpful to interpret that evidence to attach numbers under alternative scenarios.
MR. THOMPSON: Uh-huh, but the question is would it be misleading to present just Nicole Brown's individual profile frequency and not do some computation regarding the likelihood of her matching a mixture?
DR. WEIR: That is not the question you asked me. I don't know why we are computing Nicole Brown's profile frequency. Why are we doing that?
MR. THOMPSON: Well, let me ask you the question this way: Would it be misleading to do what the Prosecutors were initially advocating in this case, which is to present no number on the mixture, per se, but just to present the profile frequencies of individuals who were being compared to the mixture? Would that be misleading?
MR. CLARKE: Objection, irrelevant, also assumes facts not in evidence.
THE COURT: Overruled.
DR. WEIR: I don't know how to answer that. I'm not--I don't understand the question. Umm--there was a mixture. You either attach a number to it or you don't, but there was the evidence of a mixture. You either attach a number or not. It is not misleading not to attach a number. It is helpful to attach a number. Calculating one of the--one of the matching known frequencies is beside the point. It has nothing to do with the mixture, so I don't understand.
MR. THOMPSON: Well, let's suppose that the frequency of Nicole Brown's DNA profile on DQ-Alpha and the polymarker systems ranged from 1 in 2500 to 1 in 26,000. Do you understand that assumption, a relatively rare profile across--across DQ-Alpha and the polymarker loci?
DR. WEIR: The frequency of people who would match that profile?
MR. THOMPSON: Yes.
DR. WEIR: That that is a range of numbers?
MR. THOMPSON: Right. Do you think it would be misleading for the Prosecutors to give a number like 1 in 26,000 to Nicole Brown's profile and then to say through testimony that Nicole Brown Simpson's profile is consistent with stain 29 and give no further number?
DR. WEIR: That doesn't--that doesn't tell all the information, I agree, yes.
MR. THOMPSON: So you agree that that would be misleading?
DR. WEIR: I'm not sure I would say misleading. It doesn't--it reflects a fallacy of trying to give any of this evidence outside the appropriate framework. Unless you give frequencies attached to items of evidence, and their alternative scenarios, you cannot make a determination which in fact was the most likely scenario. So anytime you try and concoct these methods of presenting evidence outside the appropriate way of doing it, you will run into problems. I mean, you or anybody.
MR. THOMPSON: Uh-huh. And by your calculations, the probability that two randomly chosen individuals, one Caucasian and one African American, would--would match with stain no. 29 is 1 in 71; isn't that right.
DR. WEIR: That's true?
MR. THOMPSON: Right? Which is considerably higher than Nicole Brown Simpson's profile frequency, isn't it?
DR. WEIR: Yes.
MR. THOMPSON: All right. All right. And so it would be incorrect, wouldn't it, to use Nicole Brown's profile frequency as an index of the value of the fact that she was consistent with that stain, wouldn't it?
DR. WEIR: If you state it like that, that sounds incorrect to me, yes.
MR. THOMPSON: All right. Okay. Now, so it sounds like the real--the real issue here is over methods for doing these mixture calculations; isn't that--and we basically agree a number is needed to characterize a mixture, and our disagreement is how to compute that?
DR. WEIR: We haven't agreed that the number is needed, no.
MR. THOMPSON: Okay. All right. Would you agree, Dr. Weir, that in order to do the kind of calculations that you are doing on the exhibit currently on the elmo, which I believe is no. 410--
THE COURT: F09.
MR. THOMPSON: 409. In order to do the calculations on chart 409, you need to make certain assumptions?
DR. WEIR: Yes.
MR. THOMPSON: And one assumption you need to make is with regard to the number of contributors to the stain?
DR. WEIR: Yes.
MR. THOMPSON: Now, does that assumption, with regard to the number of contributors, does that assumption have to be made to do the calculations in the manner reflected on chart 410, which is the Defense's approach to the calculation?
DR. WEIR: It doesn't, but that is not a relevant fact. We have no choice. It is not a question of taste or opinion. If we want to estimate the frequency of the contributors to the mixture, we must take account of the number of contributors. I'm not sure how I can say that any more simply. It is not rocket science here.
MR. THOMPSON: Now, another assumption that your approach makes is that all alleles of all contributors can be detected; is that correct?
DR. WEIR: That's true. I have had to assume that I am not an expert in the molecular biology. I take what the forensic scientists approach.
MR. THOMPSON: Does that assumption need to be made to make the calculations reported by the NRC counsel I'm chart?
DR. WEIR: Absolutely. You can't do anything until you have a starting point which is at least found. Now, I will continue, because there are cases where we know there were two contributors, but we see less than four alleles at a locus. It shows up more clearly in the RFLP situation where some of the alleles appear either or hidden or to be not seen.
MR. THOMPSON: Let me direct your attention again to chart number--excuse me, is this 409?
THE COURT: This is 410.
MR. THOMPSON: 410, the Defense chart 410.
MR. THOMPSON: Now, based on the calculations done on this chart, Dr. Weir, would it be correct to say among Caucasians the percentage of people who have genotypes consistent with alleles observed in stain 29 is approximately 45 percent?
DR. WEIR: That is a completely misleading statement and I don't even believe it is true. "Consistent" means you can account for the stain with the people listed. You cannot account for the stain by adding up those single contributors. The first item does not account for alleles 1.2 and 4. If you--that statement you made, and I listened very carefully, I think comes very close to being dishonest.
MR. THOMPSON: Is it--is it incorrect scientifically, doctor?
DR. WEIR: Yes, it is incorrect scientifically because it is not--I take "Consistent" to mean explaining the data.
MR. THOMPSON: All right. Let's--let's instead ask the question this way: Would it be correct to say that among Caucasians the percentage of people who have genotypes that would be included in the stain observed in stain 29--included in the alleles observed in stain 29 is approximately--let me--let me start again. Based on this chart, no. 410, would it be correct to say that among Caucasians the percentage of people who have genotypes that would be included in the set of alleles observed in stain 29 is approximately 45 percent?
DR. WEIR: That statement is correct, but it is misleading in the sense it gives us no basis for interpreting the evidentiary value of this mixed stain. It is a correct statement, but I don't think it has any relevance.
MR. THOMPSON: So it is scientifically correct, but it is misleading? Is that your position?
DR. WEIR: Absolutely.
MR. THOMPSON: Now, when you say "Misleading," what you mean, I take it, is that you think it might give the jurors the wrong idea about how to think about this evidence?
DR. WEIR: I mean it is misleading in that it gives us no basis for interpreting the evidence of matching between known contributors and a mixed stain. It gives us no foundation to making--drawing any conclusions numerically.
MR. THOMPSON: Well, suppose that I, upon learning that Nicole Brown Simpson's genotypes are consistent with those found in stain no. 29, was curious to know what percentage of people in the population have genotypes consistent with those in stain 29. Isn't 45 percent the number that I need to know to respond to that--
DR. WEIR: You might want to know that, but that is not a question that we would need to be addressing here. It is not relevant. I mean that is an interesting question, I suppose, but why would you even ask it? The evidence is that there are two known contributors. They match the mixed stain. Is that--how often does that happen coincidentally?
MR. THOMPSON: All right. So your argument--
DR. WEIR: If you want to talk about Nicole Simpson, you need to consider the scenario of Nicole Simpson versus another unknown versus two unknowns.
MR. THOMPSON: Okay. So if I understand your argument correctly, you are arguing that the way the jury should think about the problem or the way anyone else should think about the problem is in terms of the likelihood of getting a pair of individuals that would match rather than just a single individual who would match? Is that your position?
DR. WEIR: Yes, I've been saying that for the last two hours.
MR. THOMPSON: All right. But, doctor, isn't that just an argument you are making?
DR. WEIR: Excuse me. I recent that completely. That is not just an argument. That is the only conceivable way of attaching a frequency to the match of two known contributors in a mixed stain. How could you possibly do anything else? And to characterize it as just an argument I think is unfortunate.
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: Doctor, you keep using this phrase "Known contributors," as in two known contributors.
DR. WEIR: Yes, I'm talking about the people not excluded. The people whose profiles we know.
MR. THOMPSON: All right. But we don't--we don't know who the contributors are of any stains in this case based on the genetic evidence alone, do we?
DR. WEIR: The known samples, yes.
MR. THOMPSON: All right. So those are assumptions? All right.
DR. WEIR: Well, that is what we have to--what the jury eventually will have to decide, are these two known people the contributors or are two other people so we are comparing those two known people with two unknown people. So that is not an assumption; that is what the trial is about, to make decisions on the origins of these stains.
MR. THOMPSON: All right. To answer questions about the number of people in the population or in some population that would have genotypes that would be included in a mixture, such as no. 29, is it necessary to make assumptions about whether all alleles of all contributors to the mixture have been observed?
THE COURT: I thought we asked that question already.
DR. WEIR: I have answered and on the RFLPs we don't--we--my calculations show that we allow for unseen bands.
MR. THOMPSON: Well, what about--let me restate the question and I believe it is a different question this time, your Honor.
MR. THOMPSON: If--if the question that I want to have answered is--is what percentage of the population would have genotypes consistent with the observed alleles, isn't it true that I don't have to make any assumptions at all about whether all alleles of all contributors have been observed?
DR. WEIR: I think I understand the question. The answer is yes and that is what I have done. My calculations assume these are the only alleles in the--in the mixed stain.
MR. THOMPSON: All right. So--
DR. WEIR: For the PCR.
MR. THOMPSON: But to do it--to do it the way reflected on the Defense chart where you are simply summing, and--and asking the question what percentage of the population has genotypes consistent with the observed alleles, we need make no assumption about whether all alleles have been observed; isn't that correct?
DR. WEIR: You don't need to make any assumptions but then you don't end up with a meaningful answer.
MR. THOMPSON: Right. Whereas under your approach assumptions do need to be made about whether or not all alleles of all contributors have been observed?
DR. WEIR: That is correct for the mixture and the single stains, is that the foundation of the whole forensic uses of DNA we have alleles seen, we calculate frequencies for them. If one was to object that that assumption, one might as well hang up their hat and go home because none of this would be possible. Of course we assume the number of contributors is consistent with the evidence.
MR. THOMPSON: Okay.
DR. WEIR: Either one or two or however many.
MR. THOMPSON: Okay. So there are two assumptions that are being made under your approach which need not be made--
DR. WEIR: I object to you characterizing it as my approach.
MR. THOMPSON: Under the approach that you have presented in your report.
DR. WEIR: Thank you.
MR. THOMPSON: There are two assumptions being made there that need not be made to use the kind of numbers that are presented in the Defense chart, one being the number of contributors and the other being the connection between the observed alleles and the contributor's allele?
DR. WEIR: For both mixed and single stains, yes.
MR. THOMPSON: Yes. Okay. Now, doctor your expertise is in drawing statistical inferences from genetic data; is that correct?
DR. WEIR: Yes.
MR. THOMPSON: One of the issues that statisticians like yourself are most concerned with is what is and isn't a logical from a scientific finding?
DR. WEIR: Yes.
MR. THOMPSON: And I often hear statisticians use the term "Permissible" as in this is a permissible--
DR. WEIR: Excuse me, I didn't hear the word.
MR. THOMPSON: Permissible, as in this is a permissible inference or this is not a permissible inference. Is that a common expression in your field?
DR. WEIR: It is not one I have heard before.
MR. THOMPSON: Oh, okay. What expression would you use to talk about an inference which is illogical and inappropriate?
DR. WEIR: I call it wrong, I suppose.
MR. THOMPSON: Wrong. Okay. Now, I gather when statisticians say an inference is wrong, it means it is illogical or fails to follow from the premises?
DR. WEIR: I imagine they would, yes.
MR. THOMPSON: Okay. And the question about which inferences are correct and incorrect, wrong or right, when interpreting scientific data, is one of the major questions that statisticians concern themselves with?
DR. WEIR: I don't see statistics as being consumed with giving right or wrong answers. Statistics is concerned with teasing out the information and sets of data, how results are often traced in terms of estimates or results of hypothesis testing. Statistics is not a black and white, right or wrong, yes or no kind of a science. It is a science of interpreting data, so I'm having trouble with understanding your characterization of statistics.
MR. THOMPSON: But part of what statisticians do is determine what is and what is not a reasonable statistical inference from data; isn't that correct?
THE COURT: Counsel, the issue is which of these two methodologies am I going to adopt for use in front of this jury.
MR. THOMPSON: Uh-huh.
THE COURT: Which makes sense both in terms of the science that produces these results and the math that is applied to it.
MR. THOMPSON: Yeah.
THE COURT: So--
MR. THOMPSON: These questions are foundational to my next line.
THE COURT: Well--
MR. THOMPSON: I will proceed quickly.
MR. THOMPSON: Dr. Weir, when drawing conclusions from a scientific tests, should an expert witness in a criminal case rely only on the scientific data or is it permissible for the expert to take into account other evidence in the case?
DR. WEIR: These--this is such a general question I don't understand it. I will say yes, but I'm not fully understanding what you are meaning.
MR. THOMPSON: Well, suppose, for example, that an expert sees a scientific test result that has two possible interpretations and one interpretation is consistent with guilt and the other interpretation is consistent with innocence. Would it be permissible for the expert to consider the overall strength of the Prosecution's case when deciding which scientific interpretation was correct?
MR. CLARKE: Objection, irrelevant to this hearing.
THE COURT: Sustained.
MR. THOMPSON: Would it be permissible for a statistician, in determining which statistical procedure is appropriate or inappropriate, to take into account the strength of the Prosecution's case?
MR. CLARKE: Same objection.
THE COURT: Sustained.
MR. THOMPSON: Dr. Weir, have you heard the term "Bootstrapping" when that term is used to refer to allowing one set of evidence to influence a supposedly independent judgment?
MR. CLARKE: Same objection.
THE COURT: Sustained.
(Discussion held off the record between Defense counsel.)
MR. THOMPSON: Now. Yeah. Have you heard the term "Bootstrapping" used in the scientific arena, as opposed to the legal arena?
MR. CLARKE: Same objection.
THE COURT: Overruled.
DR. WEIR: The word "Bootstrapping" is in my report.
MR. THOMPSON: Right. Now, I know your report refers to a statistical procedure known as bootstrapping. Have you heard an additional meaning of that term "Bootstrapping" in scientific circles?
DR. WEIR: No.
MR. THOMPSON: Meaning to draw--draw conclusions on--on--
THE COURT: Counsel, this is not real helpful to me.
MR. THOMPSON: Well, I--
THE COURT: It is really not. It is a complete waste of my time so far, this whole discussion about bootstrapping.
MR. THOMPSON: I was. I think I can tie it in, your Honor, if you will give me some leeway.
THE COURT: No.
MR. THOMPSON: All right.
THE COURT: Proceed.
MR. THOMPSON: Now, Dr. Weir, in order to compute the mixture statistics using your method--
DR. WEIR: And it is not my method.
MR. THOMPSON: Well, using the method that you are advocating, you need to make assumptions, and would you agree with me that the numbers that are produced by your method vary depending on the assumptions that you make?
DR. WEIR: You will have to be specific. I don't know what you mean.
MR. THOMPSON: For example, the numbers that you produce would vary depending on whether you assume there were two contributors or three contributors?
DR. WEIR: My report shows two tables with different numbers under those two conditions.
MR. THOMPSON: So--
DR. WEIR: I also have tables for single stains where I have assumed a single contributor. I have answered that several times.
MR. THOMPSON: And so the answer is yes?
DR. WEIR: Yes.
MR. THOMPSON: All right. And the numbers that you compute would also vary, depending on whether you assumed that all alleles of all contributors are being observed in the stain?
DR. WEIR: The answers of all the analyses in this trial depend on that assumption.
MR. THOMPSON: Okay. And so under some assumptions you get numbers that are much bigger and more impressive than under other assumptions, don't you?
DR. WEIR: I don't understand the question. You will need to be specific.
MR. THOMPSON: And have you noticed, Dr. Weir, that when you compute numbers under assumptions that are consistent with the Prosecution's theory of the case that you will get numbers that are larger and more supportive of the Prosecution's case?
MR. CLARKE: Objection, argumentative and also irrelevant.
THE COURT: Sustained.
MR. THOMPSON: Is it the case, Dr. Weir, that if you compute numbers under assumptions consistent with the Prosecution's theory of the case, that the numbers that are produced by the method you are advocating are more supportive of the Prosecution's theory of the case?
MR. CLARKE: Same objection.
THE COURT: Sustained.
(Discussion held off the record between Defense counsel.)
THE COURT: Mr. Thompson, if it is of any benefit to you, I understand the two assumptions that underlie Dr. Weir's testimony and the calculations that he makes and the fact that you will get different results depending on what the assumptions are. I understand that. I understood that an hour ago.
MR. THOMPSON: Okay. All right.
MR. THOMPSON: Let me ask you a few questions, Dr. Weir, about what your report says concerning item no. 78, and I think if you look--if you look in your report at page 25--
DR. WEIR: Thank you.
THE COURT: Refresh my recollection. Which item was item no. 78?
MR. THOMPSON: Item 78 was a stain on the bottom of Ronald Goldman's boot.
THE COURT: On the bottom of the sole of his boot.
MR. THOMPSON: It contained a number of alleles which were consistent with Nicole Brown Simpson on RFLP tests, along with a few that were consistent with Ronald Goldman.
MR. THOMPSON: Is that a correct characterization, sir?
DR. WEIR: Excuse me.