All right. Thank you, ladies and gentlemen. Please be seated. All right. Let the record reflect that we have been rejoined by all the members of our jury panel. Dr. Gerdes, would you resume the witness stand, please.
John Gerdes, the witness on the stand at the time of the noon recess, resumed the stand and testified further as follows:
You are reminded that you are still under oath. Would you state your name again for the record.
All right. The record should reflect that Dr. John Gerdes is on the witness stand undergoing direct examination by Mr. Scheck. Good afternoon, doctor.
Doctor, you are reminded, sir, you are still under oath. Mr. Scheck, you may continue with your direct examination.
Thank you, your Honor. Good afternoon, ladies and gentlemen of the jury.
THE JURY: Good afternoon.
Your Honor, we showed Mr. Clarke over the lunch the printout that I think we designated Korean database 4 contaminant that we didn't print before and that is 1286-A.
Now, Dr. Gerdes, this was the set of strips from the Korean database where you identified for us before the four contaminants in those known samples; is that right?
And in this instance, the negative amplification control, did that show any contamination or any dots on it?
Yet on these set of strips you've identified contaminating alleles in sample; is that correct?
Well, doctor, how could it be that you have contaminants on the strip but the negative control doesn't show any foreign DNA?
Well, this is--is well-known, and has been described in the national research council and obviously I have observed it in my review of the strips from the LAPD, and it basically has to do with the fact that when you have contamination and it is at a low level of contamination, you can find situations where it is not necessarily going to find its way onto those--all of the control strips. So in this particular case we can see that it is present in the items but it is not present on the strip--
Would it be fair to say that in terms of these methods that just because controls are negative for one set of experiments, that doesn't mean that the specimen strips aren't contaminated?
You mentioned the national research council report. Do you have that book in front of you?
That is the study "DNA technology in forensic science" from the national research council?
This reference that you made, would that be on page 67 or one of the places that this phenomena is mentioned?
Do you rely upon the national research council--let me direct your attention to page 67 of that document.
Do you rely upon this as an authoritative scientific test with respect to the issues of contamination in forensic PCR applications?
All right. Could I have this--shown this to counsel. Could I have this page be marked as--
I show you what has been marked as 1296. Is this page, is that an accurate reproduction of the section you just referred to in your testimony as one of the conclusions of the national research council?
All right. Your Honor, may I put that on the elmo and have the witness read it to the jury and explain it?
Could you direct Mr. Harris to mark the top strip which you identified as the negative control where there was no contamination, it was clean, but on these set of strips where there was nonetheless contamination of the specimens?
Could you mark that, Mr. Harris, on the left-hand side, "NC." All right. And could we print this out as--can we leave--
All right. Now, it says: "Moreover, it should be remembered that controls are useful for monitoring general contamination in a laboratory, not the accuracy of a particular experiment."
Excuse me, your Honor. I'm going to enter an objection as to hearsay at this point.
Is the national research council report in this section--are these conclusions the kind of data that DNA scientists in your field rely upon in forming conclusions with respect to scientific matters?
This NRC report represents a report that was put together by a panel of respected scientists and is well-known to be the consensus opinion at the time it was published and is relied upon.
Have you relied upon the NRC report in this particular section in forming your opinions with respect to this case and on the issue of forensic DNA typing?
Get back. Now it says: "Moreover, it should be remembered that controls are useful for monitoring general contamination in the laboratory, not the accuracy of a particular experiment. If a blank control is positive in one experiment, it indicates a potential problem not just for that experiment, but for any experiment performed at about the same time." Now, if I could stop right there, when they use the term "Experiment," how does that relate in terms of these PCR strips? What are they referring to?
Well, each--each--you could look at it in two ways really. Each strip could be called an experiment or the entire run would be an experiment.
So when they are saying that the accuracy of a particular set of strips or a particular experiment that one set of strips--withdrawn. When they say here: "If a blank control is positive in one experiment it indicates a potential problem not just for that experiment but for any experiment performed at about the same time," now, a blank--positive control--a blank control there, that is what we've been talking about as negative controls?
All right. So if a negative control is positive in a certain period when typing is done, what are they saying with respect to the potential for contamination on other sets of strips where the controls are negative?
They are saying that just because that one--if you have one strip that shows, or any indication of contamination, that can't be interpreted that another experiment that was done on the same day, or around the same time period even, you can't assume now that the laboratory is clean, because this is a random sporadic process. You can't automatically assume that just because the other strip is clean that the entire run that was associated with that clean strip might not be contaminated.
And it goes to say that: "Even in a laboratory contaminated with PCR carry-over, blank controls do not necessarily become contaminated on every occasion. It would be wise to repeat all work with samples that have never been exposed to the PCR typing laboratory." Now, when they say "Exposed" what in your judgment does that mean?
Well, it means exactly what it says, and that is it can't--the sample can't--should not have even entered the doors of that laboratory.
All right. It goes on to say: "In view of the problem of contamination due to handling and carry-over, laboratories must incorporate contamination controls into their standard operating procedures and outbreaks of contamination and the steps taken to correct the problem should be documented." Do you agree with that?
Referring here to 1295. Your findings as represented here on 1295 in terms of runs contaminated at the LAPD, does this represent outbreaks of contamination in your judgment?
And in terms of documentation, and I bring you back here for one second to 1296-A, the Korean database with the 4 contaminant where the negative control came out blank--
--now, did the analysts from the LAPD record the presence of a weak 4 allele or what you are calling the contaminant allele on these strips?
So in other words--and when you were finding what you've identified as contaminants on these runs, in about what percentage of the time would the analysts from the LAPD actually write down or note on the sheet the presence of the contaminant allele?
Well, how many times would you see in the records of these strips that the LAPD analyst would write down and identify the presence of what you are calling the extra allele?
Well, when you looked at these sheets of paper, would you see written on it an indication of the presence of what you've called the extra allele?
All right. And about what percentage of the time would there be on those documents written down an indication of that extra allele?
All right. I will allow this subject to a foundation for the source of these documents to be laid later.
I don't recall the exact percentage, but I would say somewhere between 85 and 90 percent of the time the allele was recorded.
All right. Now, would it be fair to say then that there was at least a record in the laboratory of what you are calling the contaminant allele?
All right. Was there any documentation that you saw on these sheets, these typing sheets, of recording an outbreak of contamination and did you receive any documents from them indicating steps taken to correct it.
There was one occasion when it was documented in the notes that the contamination was recognized and recorded. Other than that, no.
I am finished with this chart. Now, moving to the period of testing in this case--
This chart, umm--do we have--can you borrow a marker? Dr. Gerdes, this chart is entitled, "Runs and strips: Percent of contamination and/or artifact." And it indicates below "May, June and July". What year is that?
All right. Could you do me a favor--and I apologize for the chart making--could you write on the top of this, "May through June, 1994," right--right after it says "Artifacts."
Now, the period May through--I asked you to write down May through June and it has July on it?
Now, Dr. Gerdes is May through July, 1994, the period bracketing the testing done in this case?
All right. And did you see essentially the results consistent with your overall findings of contamination in the laboratory during this period?
And this chart is entitled, "Percent of contamination by control May through July, 1994." Now, Dr. Gerdes, what does this chart represent?
In this particular chart we look at the negative controls and ask the question where do we find contamination in those, and you will recall those particular controls would have no dot at all, no indication of DNA, because they--they represent negative controls, meaning no DNA control.
Now, you indicated that there are two kind of negative controls used at the LAPD. One extraction controls and the other one negative amplification controls?
All right. And this chart represents--is it your finding that 10 out of 25 negative amplification--extraction controls were contaminated during the period May through July of 1994?
Now, what does that indicate about the source of the contamination or what phase of the DNA testing process would be the source of the contamination based on these findings?
All right. What--what is the--at what phase of the DNA testing process would there be contamination in an extraction control?
The extraction control is a--as you recall, is where the analyst will use a control swab or a piece of cotton cloth and then go through the entire manipulation and DNA extraction procedure, so it is going to be a control that will detect human DNA that shouldn't be there during that manipulation stage and during the DNA extraction stage.
So would it be fair to say from your findings in the period of May through July of 1994 that the contamination in the controls was occurring during the sample handling and extraction phase of that process?
Now, Dr. Gerdes, in your review of other forensic laboratories have you made assessments of the existence or nonexistence of contamination?
In any of the 23 laboratories whose work you've reviewed and the seven laboratories that you visited, based on the data you have seen, have you seen any--how does the LAPD rate in terms of levels of contamination?
All right. In looking at other laboratories what data have you had to assess the existence or nonexistence of contamination?
I have had these--the strips for the instant case that I was looking at, plus the controls that were run around that time.
In some laboratories, yes. Specifically in Cellmark and in association with this case and at the Department of Justice in association with this case.
All right. And in terms of looking--in terms of that data, compared to the extent of contamination you saw in those laboratories, and the extent of contamination at LAPD, how does the LAPD rate?
All right. Was it at the level that you found at the Los Angeles Police Department?
Well, let's try it this way: In your judgment how serious is this problem of contamination that you found at the Los Angeles Police Department?
In terms of speaking as a DNA laboratory director, in terms of the standards used by accrediting groups such as the national marrow donor program, what action would be taken concerning a laboratory that had the level of contamination you found at the LAPD?
Are you familiar with organizations used by the donor bone marrow to assess contamination?
All right. By those standards are there remedies that accrediting agencies use when they find contamination or other quality assurance problems in laboratories?
Now, is the LAPD, in terms of levels of contamination, worse than any other forensic laboratory you've ever seen?
Now, you refer to the validation--I would like to put on the elmo then 1181-A. All right. If you recall, is this the statement concerning PCR method validation training record from the LAPD?
And I call your attention to the statement: "Every validation sample either gave the expected typing result or no typing results were observed. At no time was an incorrect typing result observed." All right. Now, did you find, looking at the validation sample run and comparing it to the chart of known typing results, that they were not the ones expected?
Well, with respect to the--did you find--how many errors did you find overall in validation studies and proficiency tests?
Okay. On May 25, 1994, there was a hair shaft, had a type recorded as a 2--recorded as a 1.2, 2 and the hair was a 2, 3 hair, so that is an incorrect type. On 9/21/93 there was a vaginal swab standard. The type anticipated was a 1.2, 1.3. It was typed a 1.2, 4, so that is an error. Again on 9/9/93 there was that same standard and it should have been typed a 1.2, 4, and it was--no, excuse me. It should have been typed a 1.2, 1.3, and it was typed as a 1.2, 4.
I'm sorry, I showed it to you before. This is what has previously been marked as 1181-C.
Is one of those sheets that you have just identified for us--you recall the testimony of Mr. Yamauchi with respect to a particular typing he did on one of these validation studies?
All right. Is one of the errors that--one of the typings that you are calling as an error, was one of those performed by Mr. Yamauchi?
All right. Could you identify which of those exhibits represents that particular typing?
Now, could you please go on and finish your description of the errors in typing that you observed.
Yes. On 7/15/93 there was a reference blood sample that was typed in error as a 1.3, 4 when in reality it was a proficiency sample that should have been a 1.2, 4. And again on 7/14/93 that same reference blood sample was again typed as a 1.3, 4, when it should have been a 1.2, 4.
Now, did you, when compiling--I'm sorry. The analysis that you've been describing for us, did you compile a table with a description of each of the strips you were examining and the typing for purposes of putting together these charts?
All right. And did you turn those over to us for us to turn them over to the Prosecution?
I don't have the original in front of me. I believe it was "LAPD DQ-Alpha contamination events" or something of that --
Because this is my raw data and it really does include that 7.9 percent of the 1.1's for instance that could be explained as DX and I--my strategy in doing this was to simply record all additional dots that should not be there, this is my raw data, and then to go back to that and analyze the data later. So it was mis--it was not correctly titled and the fact that those--that minor percentage of 1.1's that could have been explained as DX are on this table.
Now, in--with respect to the errors, when you were compiling that table and reviewing it before you came here to testify, did you make another change with respect to errors?
Yes. Originally there was a hair shaft which was from a hair of a 1.2, 1.3 type and it was called a 1.2, 4, which is an error. However, in the typing of that strip it was recorded by the analyst that there was no C dot and I felt I could see a C dot and that is why I recorded it as an error, but in fact since the analyst recorded no C they would not have interpreted that as an interpretable result and I decided to not call it an error because they would not have reported it if they didn't feel they saw the C dot.
Okay. Now, do you think it is a problem, Dr. Gerdes, for a DNA laboratory not to recognize that it has contamination in its laboratory?
Do you think it is a problem for a DNA laboratory not to recognize when it is making errors in its own validation study?
I would like to turn now to the procedures that were used for the collection and handling and processing of samples in this case. And your Honor, what I would like to do is go back to a set of slides that we used previously that are marked as 1149-A that I have shown to Mr. Clarke entitled "Cross-contamination factors."
Now, did you identify certain procedures for the collection, handling and processing of samples by the Los Angeles Police Department that in your opinion created risks of cross-contamination and error?
All right. Let's turn to 1159-B. Now, do you recall the testimony in this case where Mr. Fung and Miss Mazzola put wet blood swatches in plastic bags?
And in your opinion is putting wet blood swatches in a plastic bag in the fashion that they described they did it in this case--what consequences can one expect from the point of view of microbiology and molecular biology?
The--you are placing a wet--a highly enriched material in a plastic bag at an elevated temperature on that particular day, which is the perfect environment for bacteria to grow, and so you are encouraging, under those circumstances, the growth of the bacteria, and the bacteria are going to grow and just eat the DNA.
KEY QUOTEAnd that can, as represented in this logo, if we assume that the one represents the DNA type of the blood on that specimen, would that arrow and that arrow represent the bacteria eating away at it? All right?
In your opinion was--was there a serious risk of degrading the Bundy blood drop samples, LAPD items 47, 48, 49, 50 and 52 by the way that they were put in plastic bags in this case?
What effect do you believe putting the blood swatches in the plastic bags and then putting them in the truck and then seven hours later after their collection finally removing them and putting them in test-tubes, what effect, in your opinion, would putting them in the plastic bag for that period have?
Are you familiar with the testimony of Mr. Fung and Miss Mazzola that they collected these samples starting at around 11:30 on June 14th, put them in plastic bags, put them in the evidence truck and then later at about 6:00 in the evening finally began the process of removing the wet swatches from the plastic bags and putting them in test-tubes?
They would shut the lab down with this level of contamination.
Definitely, by far.
The contamination persists through that period.
You are placing a wet--a highly enriched material in a plastic bag at an elevated temperature on that particular day, which is the perfect environment for bacteria to grow, and so you are encouraging, under those circumstances, the growth of the bacteria, and the bacteria are going to grow and just eat the DNA.
Well, I'm an idiot. Let the record reflect I have corrected it to July.