Thank you. Now, I understand that you said that you disagree with this approach, but I'm simply asking you to do certain calculations, make certain calculations to answer this question which is what percentage of the population could be included as a contributor to this profile; namely, the 1.1, 1.2 and 4 alleles that you see on the steering wheel. And what I would like you to do, sir--
Excuse me. Your original question was "Excluded." So we're now talking about "Included"; is that correct.
No. That percentage of the population which cannot be excluded, which would be the same I believe as that percentage of the population which could be included; is that correct?
All right. And, as you know, it is Cellmark's approach when it looks at those different frequencies, it takes the highest frequency from the different databases; is that correct?
Yes. They have--for Caucasians, they have three data sets they rely on, that they have access to, and they take the highest frequency for each allele.
Now, looking at this table, sir, is it clear that the first column refers to the various potential genotypes that could contribute to the mixture found on the steering wheel?
That--that doesn't quite state it accurately. This is the frequencies of single persons that could have contributed to the stain we know came from more than one person.
And so to get a mixture, it would require the contributions of different individuals; would it not, sir?
Okay. So now what I would like you to do is to look at the individual genotype frequencies for those individuals who could contribute to this mixture.
I don't think I can do that from this chart. I don't see the frequencies of the pairs of individuals that could have contributed.
Sir, I'm asking you to calculate--I understand how you disagree with this approach. I'm simply asking you to calculate the individual frequencies. And my first question, sir, is, according to the chart that you have, are there frequencies listed in the Cellmark table for the genotype frequency for the 1.1, 1.1 genotype?
And then do they also have a--the genotype frequencies for the second genotype, 1.1, 1.2?
And just to save some time, are the numbers that I have on that table consistent with the numbers that you have on the Cellmark table?
The numbers on the shorter table are an extraction of the numbers on the bigger table, yes.
There's nothing inaccurate in my writing down recording the numbers on Defendant's exhibit 1202; is that correct?
Okay. And can you think of any other genotypes of individuals who could contribute to the mixture on the steering wheel other than the six genotypes that I've listed on the table?
Well, the contributors to the mixture of course are a mixture of people. There's no single genotype, not listed here, that did not contribute. Did I get that right? I think the answer is yes.
Okay. And, sir, if you now sum up the frequencies of individual frequencies who could contribute to this mixture, first using the Caucasian database that Cellmark relies upon, is the number 45.4 percent an accurate number of the summation of those frequencies?
Okay. And does the number 59.2 percent reflect the sum of the frequencies of individuals who could contribute to this mixture in Cellmark's African American database or table that they rely on?
And is the frequency 48.8 percent of the population the number that one would arrive at relying on Cellmark's Hispanic database?
Now, sir, what I would like you to do is go back to the question that I initially posed and then walked away from, which is, what percentage of the population could contribute that number 4 allele that we know that neither Mr. Simpson could contribute nor Nicole Brown Simpson could contribute and we know Ronald Goldman is also excluded. And I want to ask you just about that one now. Do you have another copy?
Now, Dr. Weir, again, what I want you to do is rely on the Cellmark tables. And just looking at the possible genotypes that could contribute the number 4 allele, is this slide correct in saying that the three possible genotypes are the 1.1, 4, the 1.1--I'm sorry. Let me start all over again. Would you agree, sir, with this table; that the genotypes of individuals who could contribute the 4 allele to this mixture on the steering wheel would be somebody who has either a 1.1, 4 genotype, somebody who has a 1.2, 4 genotype or somebody who has a 4, 4 genotype?
Yes. If the person was a contributor to the mixture, they must--and they gave a 4, they must have a 4 and they must not have anything other than what we see in the mixture. So that's correct.
Okay. And again, looking and relying on the Cellmark tables in front of you, sir, are the frequencies that I have here for somebody who has a 1.1, 4 genotype correct for the three different databases; namely 9.5 percent, 7.7 percent and 9.9 percent of the population?
Well, they're in a different order. They're in a different order than from what's on the chart, but at least I think they're correct. Yes, I think they are.
Okay. And are the frequencies in the three different Cellmark databases for somebody who has a 1.2, 4 genotype correct in the slide on the board?
All right. And finally, the frequencies for somebody who has a 4.4 genotype, are the three numbers up there the correct population frequencies for that particular genotype in the three different Cellmark databases?
Okay. Fine. And, sir, if you simply sum the frequencies for the various genotypes as is shown in this slide, according to Cellmark's database, would you agree, sir, that 40 percent of the African--approximately 40 percent of the African American population, according to Cellmark's database of course, has a genotype which is consistent with being a part of this mixture?
I think that's right. 40 percent is the sum of all the individual people who have one of their alleles a type 4.
And, sir, would you agree that, again, using the same Cellmark tables, that approximately 31 percent of their Caucasian--of the Caucasian population based, of course, on their Caucasian database also could not be excluded as a possible contributor to this mixture?
And finally, given Cellmark's Hispanic database, that approximately 38.4 percent of the population could not be excluded as being a contributor of that 4 allele?
Well, I do have to accompany my response by saying that that's correct, but I don't think it has any bearing on the interpretation of the mixture.
KEY QUOTEI appreciate that. Now, Dr. Weir, during your direct examination, you defended or supported shall we say Cellmark's and DOJ's use of the product rule to generate the frequencies in this case; is that correct?
Would you agree, sir, that within the fields of statistics and population genetics, there has been controversy regarding the appropriateness of the product rule as it is used, for instance, by Dr. Cotton and Mr. Sims in this case?
You'll have to be more specific. I'm not sure exactly what you're meaning. A lot of people said a lot of different things. I don't--you started talking about independence and then you started talking about controversy. So I need to understand what you're asking me.
Well, has there been controversy about the methodologies used by laboratories such as Cellmark and DOJ to calculate the rareness of a particular DNA profile over multiple loci?
Well, I'm not sure that I can answer that very clearly. There have been--there are published ways validating the procedures used. Some people have made statements critical. But the various statements are all over the board. So we need to be focused on what specific aspect you're talking about. We can discuss that in some detail.
Well, let me ask you this, Dr. Weir. When you--did you testify yesterday morning at a hearing in this courtroom prior to your testifying before the jury?
And when you testified at that hearing, didn't you say that you wrote letters to different publications because you believed that the way those publications covered the debate on these issues was one sided? Did you say that yesterday?
Okay. So when you said there was a debate, you meant that there was a debate within the scientific community; did you not?
Not quite. There was a debate--and I would classify those--that debate as being almost in the popular press. That wasn't a scientific literature debate. So I want to be clear about that. I have written letters to the editors of journals that have essentially carried news stories about this forensic uses of DNA. That's different from the scientific literature.
The debate was in the--in this--in this--the debate was not in the scientific literature.
Well, Dr. Weir, you said that you are familiar with the national academy of science, NRC, report, correct?
And this report was authored by a committee of distinguished scientists and forensic scientists and others; is that correct, sir?
And you would agree the national academy of science, which is responsible for this undertaking, is an extremely prestigious scientific organization in this country. Is that a fair statement?
And this report represents the national academy of sciences, national research council's effort to address the various issues involved in DNA technology and forensic science; is that correct?
Yes. It's a report set up by the--by that body and actually conducted by a committee of members outside their body, but it's under their ages, yes.
In fact, Dr. McKusick, who is the chairman of this committee that authored this book, is a member of the national academy of science, isn't he?
Now, aside from Dr. McKusick, Dr. Weir, there were other very highly regarded geneticists on this committee; is that correct?
And there are also highly-regarded forensic scientists on this committee; is that correct?
Well, I assume so. I'm not familiar with that field so much, but I assume they're reputable and highly regarded.
Well, you've attended some of the meetings within the forensic community over the last few years, haven't you, and given talks?
Yes. Uh-huh. I'm just--all I'm saying is, I'm not as familiar with the--with those people, but I understand that they're very good.
And based on what you know of him and what you've heard in the community, does he have a very distinguished reputation--
And then we come to Dr. Mary-Claire King. She was another member of the committee that authored this report and she too a very distinguished geneticist?
In fact, in the document which you've read, they described Dr. King's expertise is in the area of genetics as well as population genetics. Are you aware of that?
All right. And also included in the same group is Dr. Eric Lander; is that correct?
Yes. Dr. Lander and Dr. McKusick and I have a bond in common, of course, because we run the subsequent NRC committee to examine some of these issues.
--you're not on the committee that's asked to draft another report. You were on the committee that considered the propriety of setting up a second committee; isn't that correct?
We were on the committee that unanimously recommended a new report, the issue to clarify some of the problems with the present report. Yes.
And you're aware that she disagrees with you on some of these issues, aren't you?
I don't remember Dr. Zabell being there, but I've seen his name. So obviously he was there, yes.
And are you aware that Dr. Zabell also disagrees with your position on some of these issues of the correct statistical approach to interpreting DNA evidence?
Dr. Lander and I I think are in agreement on the need for a new committee. He is very distinguished, yes.
And Dr. Henry Lee was also on that committee. Are you aware of Dr. Henry lee's reputation in the forensic science community?
And he's an expert in the field of statistical inferences in evidence; is he not?
We'll get to that a little bit later, Dr. Weir. And Dr. George Sensabaugh was also on this committee, correct?
And he's also a very highly-regarded member of the forensic science community; is that correct?
And Dr. Thomas Marr is also a scientist who sat on this committee as well, right?
Well, as--not only do you know his name, but you know his reputation as a leading geneticist?
All right. Now, this book authored by the NRC committee and authored by the individuals who I just listed to you states, does it not, that there is a substantial--
Have you considered the NRC report in reaching your positions on the appropriateness of using certain statistical methods for interpreting DNA evidence?
Have you, in fact, written papers and articles or letters to people criticizing positions taken in the NRC report?
Now, I'm not asking you, sir, at this point about the correctness of what the NRC did. I'm simply asking you whether or not the NRC recognized a controversy in--
I'm simply asking you, sir, not whether you agree or disagree with the NRC's position, but did the NRC report acknowledge that there is a substantial controversy has arisen concerning the methods for estimating the population frequencies of specific DNA typing patterns?
And it is the position expressed in writing by the authors who we just described?
And I believe you said that you made formal submissions to the NRC committee, is that right, that authored this report?
Yes. You and I were in the room at the same time when I spoke to the committee.
KEY QUOTEAll right. And at that point in time, you didn't say to yourself, Dr. Weir, "I'm not going to make a presentation then because these people don't know what they're talking about," did you?
Oh, no. I was very excited about this committee. I thought it was a group of fine scientists and that we might get a document to guide us in the future. I was very pleased to be there.
And, in fact, the NRC chose to reject your opinion as to the appropriateness of the then current methods for estimating those population frequencies, didn't they?
Well, Dr. Weir, did you feel resentment about the fact that the NRC report reached a different conclusion than the one you would have wanted?
Well, I'm not sure what you're--there's no single conclusion in the document. Could you tell me which one you're referring to?
Fine. This conclusion. "Although mindful of the controversy, the committee has chosen to assume for the sake of discussion--"
That misleading statement is in the report.
You and I were in the room at the same time when I spoke to the committee.
No, I don't.
I do have to accompany my response by saying that that's correct, but I don't think it has any bearing on the interpretation of the mixture.