Dr. Cotton, with regard to 84-a, and let's start there, Nicole Brown Simpson's left nail clippings--I'm sorry, left nail--
With regard to no. 84-a the left nail clippings and scrapings, did you test that particular item?
Okay. The results from the PCR testing on 84-a are consistent with Nicole Brown Simpson and exclude Ronald Goldman and Mr. Simpson.
All right. Your Honor, with the Court's permission as to that item, the left nail clippings and scrapings, I'm going to ask for permission to remove the covers.
Turning your attention now to what is marked 84-a, the right nail clippings and scrapings from Nicole Brown, did you also perform testing on that item?
They are consistent with Nicole Brown and they exclude Mr. Goldman and Mr. Simpson.
Does that mean, Dr. Cotton, that you obtained the exact same results for 84-a as you did for 84-b, the clipping?
And then lastly, with regard to this item, 84-b, referring your attention to the right scrapings, did you also test those using PCR?
They are consistent with Nicole Brown and Mr. Simpson and Mr. Goldman are excluded.
And were these the exact same results as in the earlier two nail clippings and scrapings results?
Dr. Cotton, I believe it was day before yesterday that you described, with regard to your controls--may I have just a moment, your Honor?
You described a couple of days ago that with regard to all the controls and all of the tests that you did, that they all worked properly, with the exception of, and I think you said there were weak reactions to one sample; is that right?
Your Honor, I'm going to ask that one of the previous drawings, exhibit 254, be placed up, so that the witness can refer to it for a few questions.
All right. If you would, would you describe what you meant by those faint reactions that you described a couple days ago.
With regard to sample--the sample which was item 7, we had--we had done this PCR reaction and gotten a faint product, so we attempted to concentrate the sample and try it again. After that concentration step we picked up two faint dots in the polymarker reagent blank.
KEY QUOTENow, we have placed or had placed out here a drawing that you did entitled "PCR controls," which is labeled exhibit 254. I'm going to ask you if you would step down from the witness stand and use that drawing to describe what you have just testified to.
(Witness complies.) this is the listing of the various controls that one normally does when you do a PCR reaction. For the sample that I'm referring to, the positive control was fine and then we talked about two kind of negative controls. One is started at the very beginning of the test and carried through just as if it was a sample, and that is the reagent blank. The second is added at the time the reaction is set up and that is the negative control. In this case, with regard to the sample, it is the reagent blank control that showed two faint dots and this control was carried through and amplified at the same time a number of samples were amplified. And on its first amplification it was fine, it didn't show faint dots. Only after the manipulations that it went through along with item no. 7 that needed to be concentrated so the reagent blank was concentrated as well, at that point when it was reamplified and reanalyzed, then it showed a faint D at the D7/S8 location and a faint C at the GC location. It didn't show any other dots, it didn't give a complete type, it didn't have a C dot or an s dot, but those faint dots were noted when the analyst and a second analyst read the results and they are recorded in the case work notes.
Well, there is two ways you could interpret that. One possibility is that there was a very, very low amount of contamination in the reagent blank to begin with, so low that it it wouldn't be amplified. That is, there was a tiny amount of human DNA there, but not enough to be amplified, not enough to see anything, and then in the process of concentrating that sample, you concentrated it just enough, that is, you reduced the volume, but you didn't reduce the amount of DNA, that now you are seeing these two faint dots and they are barely detectable. The other scenario that would account for that is that the reagent blank was clean up until the point that the sample was concentrated and the manipulation of putting it through the micro--it is a little tiny thing, but putting it through this concentration step, somehow in doing that we picked up a very small amount of contaminating DNA and that is what we saw and there is no way to know which of those two alternatives accounts for obtaining those two faint dots in the reagent blank, but those are the two possibilities.
How many samples were involved in this testing that had that faint reaction in the reagent blank?
That is no. 7. Now, let me clarify that. That reagent blank was started with a series of samples and I don't remember exactly, without going back to the notes, which samples it was started with, but it was several. The most--most of the samples typed just fine, as did the reagent blank produce no type on the first amplification. So the reagent blank for those samples is--is okay. It is only--it only affects your--or you only--we only looked at it and tried to take it into account with respect to item no. 7 because that was the item that was then concentrated and then typed and actually then it was typed--the pre-concentration was typed also and all those results were consistent.
Now, as far as these controls--and first of all, did you ultimately report a result for no. 7, the Rockingham driveway stain?
The sample was amplified twice, before it was concentrated and after it was concentrated. In both instances it gave exactly the same results, and the reagent blank dots that I described, whatever they were, the faint b and the faint c, were so light that we felt this would--could not possibly have compromised the types that we saw in that sample and therefore we went ahead and reported it.
Now, on 254, you have listed at the bottom "reagent blank control." is that what we are talking about?
As far as this particular evidence was involved, did you get any reactions or see any contamination from the negative control?
With regard to your testing, is there any other evidence of contamination whatsoever in any of your tests in this case?
All right. If you could, could you have a seat back on the witness stand, Dr. Cotton. Thank you.
Dr. Cotton, you also described the fact, when you were going through one of the boards, and I believe it was yesterday, as far as some of the evidence items that you received, that you received some unstained or substrate controls as well?
As far as the Bundy crime scene, did you receive unstained controls for one of the Bundy walkway stains, no. 49, as well as the shoeprint, 56?
As a DNA analyst, is that important in any way because it was a substrate control?
Well, it tells you that the immediate--it--I don't know--I don't have personal knowledge of where that substrate control was taken, but generally it would be taken close to the stain, so it tells you that the surrounding or the area from which the substrate control, which was--if I can assume it was close to the stain, didn't have DNA in it, so that the DNA that you get from the sample is DNA from the stain.
Now, I would like to shift your attention back to the fingernail scrapings and clippings that were no. 84, that is from Nicole Brown.
Excuse me. Dr. Cotton, would you allow Mr. Clarke to finish asking the question before you start to answer.
What form did they come to you in, and I'm talking about just the fingernail scrapings and clippings?
Now, I would ask, your Honor, that be marked as the People's next exhibit, which I believe is 260, what can be described as the Bronco results board.
Dr. Cotton, incidentally, with regard to what has been described as the Bronco automobile, did you test one item of evidence from that particular location?
Sure. If I can direct your attention to what has been described as item no. 29, the Los Angeles Police Department item number and described as the steering wheel.
I'm having a little trouble going back and forth between our numbers and the item numbers.
And with regard to that mixture--I'm sorry, let's start with the DQ-Alpha results. What were they?
All right. Your Honor, with the Court's permission I'm going to remove the first magnetic cover as to item 29.
Dr. Cotton, with regard to that series of results or what is written that I have just revealed with the magnet, does that accurately describe the results you obtained?
As far as the three individuals, that is, Mr. Simpson, Nicole Brown and Ronald Goldman are concerned, can you make any conclusion about who was included or excluded from that result?
Mr. Simpson is included. Mr. Goldman is not included and Nicole Brown could be included.
KEY QUOTEAll right. Your Honor, with the Court's permission I'm going to reveal that marker.
And in fact, Dr. Cotton, should there be an additional name up there from these three parties, since there is one name at the moment?
Your Honor, with the Court's permission I'm going to simply write in that name, if that is acceptable, or ask the witness to.
For the record, I have written in the name "Brown" beneath "Orenthal Simpson" on this particular exhibit.
Now, as far as this particular item, did you also receive an unstained control for item no. 29?
Your Honor, at this time I would like to move to another board which I believe would be People's exhibit 261.
All right. Ladies and gentlemen, we are going to take a recess for the morning. This might be slightly longer than our normal recesses. Please remember all of my admonitions to you. Don't discuss the case amongst yourselves, don't form any opinions about the case, don't discuss the matter with anybody else, don't conduct any deliberations until the matter has been submitted to you. And we will stand in recess. All right. Thank you.
We obtained results that indicated there was a mixture in that item.
Mr. Simpson is included. Mr. Goldman is not included and Nicole Brown could be included.
We felt this would--could not possibly have compromised the types that we saw in that sample and therefore we went ahead and reported it.
With regard to sample--the sample which was item 7, we had done this PCR reaction and gotten a faint product, so we attempted to concentrate the sample and try it again. After that concentration step we picked up two faint dots in the polymarker reagent blank.