Dr. Gerdes, with regard to the LAPD's DNA testing in this case, you have described previously that Mr. Yamauchi conducted PCR typing in this case on June 14th and June 15th, correct?
And in that testing he used the controls that you previously described as a result of my asking questions about reagent blanks and so forth, correct?
Now, your Honor, I have another document--one more document I would ask to be marked as People's I believe 572 which I have previously shown to counsel.
First of all, this particular document or slide, as it is now on the screen, have you had a chance to see that or take a look at it last week?
And did you have an opportunity to calculate the total number of evidence samples, known standards and controls, that Mr. Yamauchi used in his testing in this case?
Now, with regard to--and there were two different dates for this testing; is that right?
They are in the sense that they are defined as coming from a single individual, and if you can find evidence of human DNA, additional human DNA, that is evidence of contamination.
So that if a person was A, let's say a DQ-Alpha 1.1, 1.2, and you saw a 3 and a 4 showing up in addition to the 1.1 and 1.2, that is again another opportunity for contamination to signal itself at least in that sample?
Now, as far as the total number of samples typed by Mr. Yamauchi, is it correct that including both June 14th and June 15th he typed a total of 42 different samples?
That consisted of eighteen evidence samples, whether it is a stain from the sidewalk at Bundy or a sample from the Bronco, correct?
He also typed the three known standards from the three individuals in this case; Mr. Simpson, Miss Brown and Mr. Goldman?
And is it also correct that the total number of controls used in this case by Mr. Yamauchi on June 14th and 15th was 21?
Is it then correct that of the 42 samples typed by Mr. Yamauchi in this case on June 14th and June 15th, half of them, that is fifty percent, were controls?
All right. Thank you. Now, Dr. Gerdes, you have, last Wednesday and Thursday, repeatedly used terms like my interpretation, possibility and risk. Do you recall using those words?
And that was in reference to your testimony about the dangers of contamination in this case, correct?
Well, if there were adequate blind proficiency studies at least you could have some idea about error rate, which would give you some idea of risk, and the other thing that you can do is, as I have done here, you can look at all of the testing around the time frame of the testing done on an instance case and see how many times errors were made and how many times there was evidence of contamination so they are--those are objective ways of measuring the amount of risk. But as to coming up with a number that is a specific number that is going to say eighty percent of the time you will make a mistake or something like that, no, you can't quantify it.
And in fact you testified about what you believe to be errors in the laboratory and we went through each of the five, correct?
Now, as far as your laboratory's work in diagnosis of diseases, you produce results that ultimately to go a doctor, correct?
And a doctor is required to notify that patient of risks no matter how unlikely they are to occur, correct?
Well, I certainly did not review specific documents as to those things outside of my field, but I am aware of them because of media coverage and just like anybody else would be.
You have also testified that it is ultimately for the jury to decide the reliability of the scientific evidence in this case. Do you recall saying that?
Is it also correct that it is ultimately for the jury to decide whether in fact any contamination occurred in this case?
All you have told this jury is that there might be contamination in this case, correct?
I believe I have documented as precisely as I can the level of contamination that exists, and from that point on I have suggested how that may have or tried to explain how that would have an impact on the case. From that point on it is up to the jury to deal with that--that piece of evidence and in the context of the whole case.
And you have talked about, Dr. Gerdes, possibilities, not what actually happened, correct?
You have spoken, you have described what you had believed to be possibilities in this case; is that right?
I have, as objectively as possible, evaluated the level of contamination at LAPD, the errors that I felt were a result of that, the evidence of cross-contamination in the reference samples and the implications of that in terms of the evidence in this case. That is what I have attempted to explain.
I don't have a hundred percent assurance that this did happen. I have no scientific confidence that it couldn't have happened.
KEY QUOTEDr. Gerdes, the results in this case from three different laboratories are consistent with the Defendant's blood being left at the crime scene, aren't they?
They are consistent with mixtures of DNA from the Defendant, Ronald Goldman and Nicole Brown being found in the Ford Bronco; isn't that correct?
Incidentally, you haven't suggested to this jury that the Defendant's reference sample cross-contaminated the evidence taken from the Bronco, have you?
The fact that I have some indications of cross-contamination in those reference samples obviously increases again the risk that it could cross-contaminate something else.
Dr. Gerdes, what I'm asking you is you haven't suggested to this jury that the Defendant's reference sample cross-contaminated any evidence in the Bronco, have you?
It is hard to tell. I mean, I have no evidence--specific evidence, hard evidence of that.
I have some--some evidence that the reference samples themselves may have cross-contaminated. At that point everything becomes suspicious.
Dr. Gerdes, what I'm asking you is you don't have any evidence whatsoever that the Defendant's reference sample cross-contaminated any of the stains from the Bronco?
Where in the history of these samples did the Defendant's reference sample come into even potential contact with the Bronco evidence samples?
There are other items that were collected at that residence who arguably may have come from the Defendant and it may not have been the reference sample, but it may have been some of those items.
Dr. Gerdes, what I'm asking you is with regard to the Defendant's reference sample, when did it come into any potential contact with the Bronco evidence stains?
The results in this case, Dr. Gerdes, are consistent with the Defendant's blood leading up to and inside his home on Rockingham; isn't that correct?
Those results are consistent with Nicole Brown and Ronald Goldman's blood being found on the glove at Rockingham, correct?
Dr. Gerdes, didn't you concede last week that the RFLP matches to the two victims on the glove were correct?
Dr. Gerdes, isn't it true that the DNA type results from the laboratories in this case are consistent with Nicole Brown's and Mr. Simpson's blood being on the sock found at the residence?
You look at more than one probe because a father might be excluded as being the father of a particular child, correct?
And you are looking at each of those markers, this is a potential father or this person who might be the father excluded as the father of that child, correct?
Once you look at those probes, you then estimate how rare is that match at one probe?
Dr. Gerdes, one of the concerns you have experienced in forensics is the fact that a sample may be small and you may not be able to retest it, correct?
Now, as far as errors--and you described how in medical diagnostics if a patient dies because of a misdiagnosis you know you have made a mistake; is that right?
And you described the fact last week that in your view there is no independent way of assessing whether or not mistakes are made in the forensic setting? Do you recall that?
I'm not aware of any evidence that hasn't been handled by the LAPD that can be retested.
Dr. Gerdes, are you aware of remaining evidence in this case that can be retested?
And in fact there are remaining swatches from many of the very items that we've described that you have described during your testimony in this case?
Well, as far as the difference between the testing, you do in your laboratory and forensic labs do, you have testified the only difference is the nature of the specimen, a bloodstain versus a blood vial, correct?
No. I believe I testified that it is comparing apples and oranges, that it is a completely different set-up and statistics involved in paternity from forensics, they really are not the same other than the fact that the methodology itself as far as how you run the gels is the same.
In other words, if you test a sample and a genetic marker, someone is excluded as having left a sample at a crime scene, let's say, numbers don't mean a thing?
As far as in your laboratory, you have tested the DQ-Alpha marker before, correct?
And in that testing did you feel competent to perform that testing of the DQ-Alpha marker?
Yes, I could do that, but the--the difficulty is, as we have discussed over and over, whether that sample--you need to have confidence. The difference in the way I do things and the way forensics does that is I have confidence that a specimen I'm working with came from a single individual, and the complications in terms of statistics, interpretation, potential error, that is introduced by the fact that these are mixtures or potentially mixtures. That is the issue.
Dr. Gerdes, if one of those samples from the Bundy blood trail, 47 through 52, if one of those was typed and it revealed a genetic marker, and I am referring to the remaining evidence, that excluded Mr. Simpson, wouldn't that be important?
KEY QUOTEWouldn't reanalysis of these samples support, if they produced exclusionary results, support your opinions in this case?
Is it your view then that if further testing in this case revealed Mr. Simpson was excluded from item 52, that wouldn't support any of the opinions you've offered in this case about forensic DNA typing?
In my opinion, with the risk of contamination, there would be no possible PCR interpretation possible at this point, because the samples have been handled in the way they have been.
KEY QUOTEI don't have a hundred percent assurance that this did happen. I have no scientific confidence that it couldn't have happened.
It didn't.
In my opinion, with the risk of contamination, there would be no possible PCR interpretation possible at this point, because the samples have been handled in the way they have been.
Dr. Gerdes, if one of those samples from the Bundy blood trail, 47 through 52, if one of those was typed and it revealed a genetic marker...that excluded Mr. Simpson, wouldn't that be important?