Back to the drawing board. I like that. Dr. Cotton, just a few more questions at the board. You have described the basic method by which frequencies are calculated for a single marker; is that right?
You calculate the frequency for the bands in the first marker. That pair of bands calculate the frequency for the pair of bands in the second marker, and to determine the overall frequency for those--that combination of bands from the first marker and the second marker, you multiply those frequencies together.
Now, you mentioned--and if you would describe--the fact that you make an assumption not--well, let me rephrase that. You've described the fact that in using these multiple markers, more than one genetic marker to calculate a population frequency estimate--and you made a comment about the necessity that they not be related to one another in some fashion. Have I characterized that correctly?
You're close. That they not be--that--the assumption is that they are inherited independently.
It means that--umm, let me use a very sort of trivial example. Suppose you were looking at a combination of how many people had red hair and green eyes. What it would mean is that the trait for hair color and the trait for eye color didn't affect one another. That is, if you had red hair, you wouldn't automatically have green eyes. Hair color and eye color aren't really a great example of that, but the point--the point works anyway. That is, umm, you don't--you can not and should not multiply these characteristics together if the inheritance of one of them is somehow connected with the inheritance of the other.
Okay. And that's the general concept of using multiple markers in an appropriate fashion?
While I have you at the chart and kind of as a last area, you've given this example of calculating frequencies or how that calculation process is done at one genetic marker. Can you actually give us an example by assigning some frequencies to, for instance, two of the bands as one of the sam--excuse me--on one of the samples and then calculate the approximate frequency at that genetic marker?
--and we say that--we'll just draw it down here. And that the frequency for this band was the band that's 5,000 base pairs was .3 and the frequency for the band that's 2,000 base pairs is .1 and a factor of two gets added to this or actually multiplied is what I need, that falls out of the fact that for any combination of two characteristics, there's two ways you can get that combination. And in this example, you could have inherited the upper band from your mother and the lower band from your father or you could have inherited the up--the reverse, the upper band from your father and the lower band from your mother, and that results, when you do the math, in requiring that you have a factor of two here. So for the frequency for the pair of bands in sample A, it would be two times .3 times .1.
And would that mean that that's the approximate frequency in your example of having those two characteristics in various populations or a single population in this example?
That's right. Based on our little tiny database here and assuming I did that in my head correctly, it would be .06.
Now, Dr. Cotton, did your laboratory receive evidence in this case before the Court today?
As far as receiving that evidence, when it first--well, first of all, did it arrive on the same date or different dates?
I'm going to show you, if I may, a series of boards that appear to depict or appear to include photographs of various containers of evidence. Have you had an opportunity to look at some boards that I just described before today?
And did you have the opportunity to look closely at those photographs to compare the items shown in those photographs as well as the dates found on those boards and compare those to your own records from the laboratory as to the dates various items of evidence were received at your laboratory?
All right. And referring initially to a large board marked People's exhibit 177-A, and in particular with respect to what appear to be three specific items that are numbered off to the left, item no. 7, 12 and an item marked "O.J. Simpson blood exemplar," did you have an opportunity to look at those photographs and the dates that are listed un--I'm sorry--under the column marked "to cellmark"?
Did you receive each of those three items on the date after the date noted to the left of the photographs under the column "to cellmark" for those three item numbers?
Yes. That's right. That--I went to our records, to the case folder. I looked at the sheets that were used to log in the evidence which record the date the evidence was received, and for each of those items, the date we received it was after the date that's displayed on the chart.
All right. I'm going to ask you to look at another chart which I believe is exhibit 177--the letter I'll have to wait on--b as in boy.
On this particular board, exhibit 177-C, and particular with reference to what's listed on the left as items nos. 47, 49, 50, 52 and 56, did you receive those particular items of evidence on the date--I'm sorry--the day after the dates listed on the column for each item labeled "to cellmark"?
All right. Then if we could move to the next board, which I believe is 177-D as in David.
And referring you to 177-D, in particular, the items that are labeled, "Nicole Simpson blood exemplar," "Ronald Goldman exemplar" and "item no. 78," did you receive those items on the date--I'm sorry--the day after the specific dates listed under your column or under that column labeled "to cellmark"?
With regard to item no. 78, can you tell us exactly what that item contained when it was received in your laboratory?
As far as this term--well, strike that. As far as the items on this board as well as the previous boards, did you at an earlier time look at the actual photographs up close to verify what's labeled on the various containers?
Yes. When I looked at the boards earlier, I checked for the initials of our analyst and the written dates on the envelopes as they're depicted, and I can read--I could read them off the photographs, and then I can check them--could check them against our records.
That was what I was going to ask. Did you then compare them to your own laboratory records of the various items as they were identified to your laboratory as well as the days they were received?
Lastly, Dr. Cotton, referring you to what I believe is marked People's exhibit 209, which lists in particular off to the far right what appear to be four photographs of items that, according to the chart, were directed to your laboratory on April 3rd, 1995--first of all, have you had an opportunity to look at the photographs on this board as well?
Now, as far as the evidence that you received and these various items, with the exception of what's listed on this latest board, 209, were received in your laboratory and you were requested to test those various items?
First of all, what was the type of evidence that was contained in most of these envelopes?
Is that a common means of transmitting evidence from one location to another for typing?
Is it common that materials or evidence such as that be shipped at room temperature, ambient temperature as you've used that term?
Once those items were received in the laboratory, were they identified in the manner that you described earlier that evidence is identified when it's received in the lab?
Now, I would like to return, if I could, to your description of the earlier visit that included that by Dr. Blake and Dr. Lee.
You described the fact that there was evidence actually cut by Dr. Blake; is that right?
I assume that came at a time after the evidence was received in the laboratory by your lab?
I don't independently recall the date right now. The notes made by the analyst reflect that the cuttings were made on 7-28-94.
Can you tell us exactly which items of evidence, that is by item number-- first of all, can you, in referring to the documents in your laboratory, describe for us item numbers as used by the Los Angeles Police Department?
With respect to this cutting that occurred on this date that you've just described by Dr. Blake, can you tell us exactly which items were cut by him?
Now it's going to--let me just pull out from the binder the right pages so I don't have to keep moving back and forth.
The items that were dealt with on that day would have been-- you want me to just list them?
Okay. Would have been item no. 78, item no. 56, item no. 52, item no. 47, item no. 12 and item no. 7.
With regard to these specific items, are you aware that item no. 78 was stained, blood-stained material taken from the bottom of Mr. Goldman's boot?
With respect to item no. 56, are you aware that that's blood staining removed from a shoeprint found at the Bundy residence?
With regard to item no. 52, are you aware that that was a bloodstain recovered from the walkway or actually driveway of that same Bundy residence?
Going back to this cutting process by Dr. Blake-- first of all, Dr. Blake is not a member of your laboratory, correct?
Is an individual not employed by your laboratory cutting on evidence in your laboratory a part of your protocol?
As far as a cutting-- and first of all, can you tell us approximately how much was cut off by Dr. Blake of these items of evidence?
Now, without going into the actual number of swatches for the other five items, that is other than item no. 78-- first of all, did the number of swatches for each item vary?
Did Dr. Blake cut off 10 percent of each and every swatch amongst this group of six evidence items?
And as I--you I believe testified earlier, those 10 percent portions were maintained in the custody of your laboratory?
This 10 percent portion, is there anything unique about 10 percent? In other words, is that a number that was just kind of picked out of thin air or what?
As part of our routine procedure, we normally set aside 10 percent of every sample whenever possible for future testing. So we made the Prosecution aware that we intended to do that, and some things followed, and following that was the Court order that Dr. Blake would take the 10 percent cuttings. So I have assumed that the 10 percent arose from our initial information that that's what we would normally take.
Okay. When you say you would normally take 10 percent of a sample, is that in any other case? You'd do that yourselves?
In every case, whenever the size of the sample allows, we will save 10 percent of the sample for future testing.
Do you have a term that you use to describe that 10 percent that you save when you're able to?
In the notes, it's just referred as a "FTS sample," FTS just standing for future testing sample.
Are there circumstances in which you're unable to keep 10 percent for future testing purposes?
Umm, basically there's two. One would be that the sample was simply so small that there was no way to physically remove 10 percent and still have enough left to test. Another thing--for example, if you had a single hair, you can't cut off 10 percent of the root of the hair. It's just too small to deal with. And the other circumstance would be, we might take a 10 percent cutting, have trouble with the original 90 percent and then go back and ask our client permission to use the remaining 10 percent; and if given permission, then we would go ahead and do that.
As far as the keeping of this future test sample or 10 percent cutting, is it kept for any purposes other than simply your ability to go back and use it if necessary?
The future testing sample, this 10 percent, is just available for whatever future testing might be done. It's not-- I'm not saying that it's just for our, Cellmark's own future testing if we have a problem. The 10 percent is set aside. Should that 10 percent be--that 10 percent could be given to another laboratory working for either side to be tested later on.
KEY QUOTENow, with regard to--and I'm referring now to the samples other than this initial set of six where Dr. Blake actually performed the cuttings. Did you take future test samples on the remaining items of evidence?
Did you also receive known samples, that is known bloodstains from identified persons?
We received three known bloodstains. The actual identification of whom those bloodstains were from was not made known to us at the beginning and they were just identified as exemplar c-1, exemplar c-2 and exemplar c-3.
So these known or three known samples were basically not known to you in terms of who they came from although you were made aware that they represented reference or standard samples from known people?
All right. Mr. Clarke, I need to stop you at this moment. We need to take a five-minute comfort break at this time, ladies and gentlemen. So let me ask you just to step back into the jury room. And, Dr. Cotton, you can step down and stretch your legs, and we'll take a brief recess.
You don not and should not multiply these characteristics together if the inheritance of one of them is somehow connected with the inheritance of the other.
Nope. Proceed. It's done by Court order, correct?
The future testing sample, this 10 percent, is just available for whatever future testing might be done... The 10 percent is set aside. Should that 10 percent be — that 10 percent could be given to another laboratory working for either side to be tested later on.
The actual identification of whom those bloodstains were from was not made known to us at the beginning and they were just identified as exemplar c-1, exemplar c-2 and exemplar c-3.