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. Good morning, ladies and gentlemen.
THE JURY: Good morning.
Your Honor, the Defense calls Dr. John Gerdes.
John Gerdes, called as a witness by the Defendant, was sworn and testified as follows:
Please raise your right hand. You do solemnly swear that the testimony you may give in the cause now pending before this court, shall be the truth, the whole truth and nothing but the truth, so help you God.
Please have a seat on the witness stand and state and spell your first and last names for the record.
Dr. Gerdes, could you tell the ladies and gentlemen of the jury what your present position is.
I'm the clinical director of a company called Immunological Associates of Denver, IAD for short.
Yes, I actually have three titles; the clinical director, the director of DNA paternity testing and the director of research and development.
And could you tell us what kind of a company IAD is and what it does in the Denver area?
Yes. Immunological associates of Denver is a reference laboratory for the purpose of supporting transplantation, organ transplantation. We do the HLA typing which is used to match the organs, solid organs and bone marrow of donors to recipient. We do clinical testing to ensure that those particular donors of organs are free of infectious agents and we do paternity testing for the purpose of legal conflicts.
In your work do you use the technique known as RFLP or restriction fragment length polymorphism analysis?
Now, I would first like to discuss with you your clinical work. You indicated that IAD does transplant work in the Denver area. Incidentally, how many hospitals are there in the Denver area?
I'm not sure how many. There are four hospitals that we work specifically with that do transplants.
All right. And so for those four hospitals your lab is the one that does the typing for purposes of the transplantations?
First I would like--you mentioned bone marrow transplants. I would like you to explain for us exactly what that is and what your work entails.
Well, the major reason an individual would need a bone marrow transplant is if they had cancer, for instance, and leukemia or other kind of cancer. When a person needs a bone marrow transplant it is critical that you have an exact match of the immune system of the donated marrow to the recipient or they will reject the donation. So a registry has been formed by what is called the national marrow donor program and individuals can basically donate a blood specimen which is typed and that HLA type is then recorded. They are put on this list which is the registry and then if an individual has cancer and needs a bone marrow transplant, the registry can be searched to find an exact match.
Let me stop you right there. When you say that--so a donor, somebody would sign up to be part of the bone marrow registry and gives a blood specimen; is that correct?
Now, you say that it is typed. Who does that mean and what technique do you use to do it?
Well, this is a national program, the national marrow donor program. They contract laboratories that do the typing and it is done by PCR-based DNA methodology.
Well, an individual with cancer is--needs a--it is determined that they need a bone marrow transplant and so that particular individual with cancer would be typed again by DNA-pcr based methods.
By our lab, in the Denver area, at least. Patients in the Denver area would be typed by our lab and then the registry would be searched to determine if a match could be found and at that point both individuals are retyped to double-check that the--everything was correct and they would proceed with the--the bone marrow transplant.
And your role is to--is to supervise that these three different stages of typing are done correctly and then when you indicate that everything matches, you essentially give the go ahead?
And that is--now, what kind of system are you using for this typing? Is that the HLA system?
HLA stands for human leukocyte antigen and that particular gene system is the one that is critical for immune recognition.
And so that is the critical gene that needs to be matched in order to prevent the recipient from rejecting the marrow donor?
Now, we've had a lot of testimony in this case about the DQ-Alpha reverse dot blot system?
That was used by I guess the three different laboratories in this case; the Los Angeles Police Department, the Department of Justice and Cellmark. Is the DQ-Alpha system in some way related to the HLA system that you use?
Yes. That particular gene is one of the HLA genes. It is actually a cluster of genes all on chromosome 6. It involves DQ-Alpha, DQ-Beta, DR-Alpha and Beta and DP.
Okay. Now, besides bone marrow transplants, you mentioned that your laboratory does solid organ transplants?
Umm, the situation in a solid organ transplant is that we don't have as much time, so basically an unfortunate individual may have an accident and then be declared brain dead and at that point we have four to six hours to type that particular individual and then there is again a registry of individuals waiting for solid organ transplants and then we would contact that individual and proceed with the transplant. But you have--the difference is it takes--you have a four- to six-hour window of time in which to basically do two things: One, we need to type by HLA to be sure that we match directly, and the second thing we need to do is we need to screen the donor for dangerous infectious agents. You don't want to obviously give someone an organ from an individual who is infectious, so I would have to screen for such things as HIV which causes aids, hepatitis, HTLV and a variety of infectious agents, that it is important to be sure the donor does not have an infection with those agents so it doesn't transfer.
So in other words, like I guess Mickey Mantle, the sports star recently had a transplant?
But your--your role is if it happened in Denver, your laboratory would have done all the typing and looking at the registries?
Now, you were talking about typing for these infectious diseases that the donor might have, such as HIV, HTLV, hepatitis b and C. Are you yet using PCR techniques for that aspect of the solid organ transplant typing process?
Well, as my--one of my functions, as the director of research and development, we are attempting to validate PCR-based methods to look for those infectious agents. At the present time we use what are called serological methods which look for the antibody and that simply says that an individual has been previously exposed and therefore might be infectious. If those types of assays are available, they are--
Those--those--those are FDA-approved and available. What we would like to do, though, is look directly for the infectious agent, that is certainly the better way to do it, and PCR is an exquisitely sensitive method and therefore has the potential of looking directly for the infectious agent. The difficulty is basically two-fold: No. 1, the time frame that we have, the five to six hours, most of the highly sensitive PCR methods take a little longer than that, usually overnight. We need to develop a system that has the ability to detect very small amounts of virus in a very short period of time.
Let me stop you right there. You say "Very small amount of virus." Is a virus a string of DNA?
When you say "Small," we have had a lot of testimony here about nanograms and then a smaller unit of that, picograms. What levels are you talking about here?
Could you just define for the jury the difference between a picogram and a nanogram of DNA?
Okay. So you are looking at very small amounts of DNA for these different infectious viruses in trying to develop a PCR technique that can deal with it; is that correct?
That's correct. So the first problem is being able to detect the very small amount. The second problem is being able to ensure that that can be done reliably and that is so that you don't have what are called false positives or false negatives. A false negative would mean that an individual might have a small amount of virus and for whatever reason we missed it, and that would be disastrous, because then the organ would be transplanted and someone would unfortunately come down with infection. The false positive would be a situation where because the technique is so sensitive, sometimes DNA from the laboratory or DNA from wherever, from previous amplifications, for instance, in the lab, might get into the tubes that we are using to test the donor.
Is contamination an issue that you are trying to deal with in developing this particular PCR technique?
Let's move on to the next thing that your lab does. You mentioned after the transplants are performed does your laboratory do something with respect to infectious disease screening?
Well, once a patient has been--has received a transplant, and it is either solid organ or bone marrow, they have to undergo what is called immunosuppression in order for us to prevent rejection. And so these individuals, their immune response is not quite as good as a normal individual and they therefore have an increased susceptibility to infectious agents. So there are certain infections that a normal individual or an individual who hasn't been immunosuppressed would not be susceptible to, wouldn't cause a problem in any way, but in these individuals it can kill them. And the primary example of that is something called cytomegalovirus.
CMV for short and this particular infection, all of us at least eighty percent of us, have seen this infection sometime early in life and it is not a problem until you receive a transplant and at that point it can become an active infection again, cause pneumonia and kill the patient, so it is a very, very difficult virus to deal with. It is also a difficult virus to grow. It takes six weeks to grow it in a laboratory, so that is not going to be helpful. PCR is the best way to look for it.
We studied 48 renal transplant, that is, kidney transplant patients, and looked at them in a way that we could validate a PCR-based method for the purpose of diagnosing early detection of the CMV virus.
Now, you indicated that you were working--you were head of research and development at IAD; is that correct?
All right. Have you--I suppose part of that research and development was your work in developing this technique, this PCR technique to detect the CMV virus?
All right. Have you recently received any other grants relating to the PCR technique and the issue of contamination that would be relevant to share with the jury?
Well, just this last month I received a grant from the advanced technology program, which is a division of the National Institute of Standards and Technology, and the purpose of that grant is to develop a new diagnostic technique that is going to be more cost effective and less complex and allow for a better way to prevent contamination.
It is a department--and I'm not sure what major department it is under--of the U.S. government and they are charged with the purpose of developing technology that will be important to the U.S. in the future in terms of keeping the U.S. at the forefront of technologies and maintaining the U.S. as a competitive country.
This was a focus program specifically asking for grants on DNA. I believe there were 27 applicants.
All right. And could you tell us what technique you use and what is involved in that?
Yes. In paternity testing we use the other type of DNA testing which is called RFLP which I believe you've all heard of, restriction fragment length polymorphism, and that technology then is used for our purpose of determining whether a child--whether an individual is the father of a child.
Now, in the paternity testing area, do you have to deal with--do you have guidelines with respect to handling of specimens and chain of custody issues such as that?
The CMV is a virus only so that involves PCR. We also look for another organism called chylmadia. It is actually not a virus but it is a microorganism that causes sexually transmitted diseases. And our function as a virology lab is to look at infections, not restricted only to infections in transplant population, but in the O.R. population or other populations as well, wherever they would need it and, that is one of the particular organisms where we use PCR.
The food and drug administration, and for clinical testing, if you use a kit, it has to be approved by that organization, and basically what that--
Excuse me for one second. A kit--is the PCR/dq-alpha technique being used here, is that a kit as well?
Now, does the kit that you use for chlymadia, does that have a contamination control?
Now, doctor, I would like to talk a little bit about your educational background. Where did you get your undergraduate degree?
I received a bachelor of science in microbiology from the University of Wyoming, Laramie, Wyoming.
I received my Ph.D. degree from UCLA in Los Angeles in the field of microbial genetics and pathogenesis and microbial genetics is what is now called microbiology.
And in microbiology, your background, what is the importance of something known as aseptic technique and could you explain what that is to the jury?
Well, aseptic technique or sterile technique is the foundation of microbiology really. It is a--basically teaching you the common sense of how to handle an item, a specimen, in such a way that you can look at what is only in the specimen and not worry about other microorganisms that are floating around the air falling in there and confusing what you are looking at.
Yes. In microbiology you have to handle specimens--for instance, if you are--if a doctor takes a specimen from you, it is very important that that specimen is transported to the lab, handled by the laboratory personnel, analyzed by the laboratory personnel and that a result is obtained from those personnel in such a way that I can guarantee, no. 1, the specimen really did come from you. And no. 2, that there wasn't some sort of mix-up of all the other specimens that came into the lab that day, which is pretty much saying the same thing. And no. 3, that there isn't a problem with the fact that we are dealing with those microorganisms day after day in the labs, some of those from the laboratory getting into your specimen and causing a false positive result.
I looked at fibrio cholera which is the organism that causes cholera, which is an acute diarrheal disease which is a major problem worldwide.
My postdoctoral work was at again UCLA and this time in the field of virology and I investigated the genetics and the molecular biology of herpes simplex virus and specifically asking questions about what it is about that virus that allows it to, once it is into the body, go into what is called a latent stage, which means that it--the infection is shut down but the virus persists.
Yes. The support for my post-doc was a competitive postdoctoral fellowship from the NIH.
So you have to compete to get that grant in order to support your postgraduate work?
Umm, I'm not very good with dates. I believe it must have been around 1978 or in that area.
I was an assistant professor at the University of Colorado health sciences center which is a medical school in Denver, Colorado.
I was again--I had two laboratories. One of the laboratories continued my work with herpes simplex virus and I was also--the second laboratory involved the investigation of the potential of viruses being the cause of multiple sclerosis.
Now, I would like to turn for a second back to your work at IAD and discuss with you some laboratory practices and accrediting and how it works in this field. Are there accrediting agencies that set standards for your DNA laboratory?
Well, CLIA is actually the law. Clinical laboratory improvement act is the--that is what the abbreviation stands for. That is a law that was passed to regulate and improve clinical testing in this country. It is administered by the health care financing administration or HCVA, and we are inspected by that organization to ensure that we are complying with the law.
Do they look to see, in the course of their examination of your quality control and quality assurance, whether there is--your laboratory adequately detects and controls contamination in your PCR work?
Is there another organization that accredits you called the American Society for Histocompatibility and Immunogenetics?
Hold on. Doctor, if you would, would you let the attorney finish asking you the question before you start to answer. The problem is the court reporter can only take down one person at a time. This is touch stuff for a court reporter.
In the course of the examination of the quality control and quality assurance documents and the case work, do they make an assessment as to whether or not your laboratory adequately detects and controls contamination?
They rely on ASHI for the accreditation process. Their additional quality control includes blind specimens that are incorporated in every batch of typings we do.
Well, we will get back to this later, but is that what has been discussed here as an external blind proficiency test?
All right. We will discuss that later. Now, what about the American Association of Blood Banks? Is that an accrediting agency that looks at your laboratory?
Do they review AABB and what is known as CAP or College of American Pathology proficiency testing?
Do they examine chain of custody rules and specimen handling rules with respect to paternity testing?
In addition to these inspections, what kind of proficiency testing does your lab go through? Just describe the programs. You mentioned already, and we will get back to it later, the national marrow donor program external blinds?
Umm, in the--there is proficiency for virtually every area that we do through the College of American Pathologists or CAP. That is a main--a major organization. That is one of their major functions is providing that kind of proficiency testing. In addition, we have proficiency testing through a number of HLA organizations, specifically for DNA HLA. One of them is called a DNA--the UCLA DNA exchange and a second one is the southeast organ procurement foundation or c-op proficiency testing.
I'm a member of the American Society for Microbiology. I'm a member of the Clinical Ligand Assay Society.
That is the major scientific organization for the purpose of microbiology and molecular microbiology or molecular pathology.
And in those meetings and conferences is a discussion of DNA laboratory techniques?
This is an organization, a scientific organization which is a collection of individuals who are involved in clinical chemistry and clinical testing.
And at those meetings do various DNA laboratory directors discuss techniques and laboratory methods?
And what--and they--at those meetings do DNA laboratory directors there discuss various techniques?
That is the organization that deals with the immunology of looking at the HLA gene.
And when you get together at those meetings are there discussions of DNA lab directors there as to techniques and standards in the laboratory?
And what is the Pan American Society for Clinical Virology? That is another organization you are a member of?
That is the scientific organization which is a collection of individuals who do virology, looking for viruses in a clinical setting.
Again at those meetings do DNA lab directors who do the PCR-based tests for looking for these infectious diseases that you told us about, such as hepatitis, HIV, et cetera, do they discuss DNA laboratory techniques, standards, specimen handling method?
Okay. Now, I would like to turn your attention now to forensic DNA typing. Have you visited and inspected any forensic DNA laboratories?
That's correct. I visited the Los Angeles Police Department DNA lab, I've visited the Department of Justice in Berkeley.
Correct. I visited the New Mexico crime lab, I visited the Denver Police Department, and I visited the Bureau of Criminal Apprehension in Minneapolis.
And how many DNA laboratories overall have you reviewed protocol and examined case work?
All right. And in addition to Cellmark, the Los Angeles Police Department, the Department of Justice, the New Mexico Police Department, the Denver Police Department, Genetic Design and the Bureau of Criminal Apprehension in Minneapolis, what other labs have you reviewed their protocols in case work?
You will have to help me on the list. The FBI, San Diego Police Department, Forensic Science Associates, and if I could look at my CV it might be--
Yes. I haven't visited; I have reviewed their protocol. They are from Texas, that's correct.
Are you--have you become familiar with the literature on the application of DNA techniques to forensic?
Over the last five years have you testified as an expert witness in a number of states on the application of DNA techniques to forensics?
Now, how did you get involved in testifying in cases involving the forensic application of DNA techniques?
Well, back in 1990 there was a case in the Denver area and as a part of--there was DNA involved in the evidence of the case and the--one of the attorneys involved in the case, I think he essentially looked us up in the yellow pages and it said that we did DNA testing and called me and asked me to look at the evidence and I--I agreed to do that and looked at that particular case. I expressed some concerns about specifically some problems that I felt there might be with PCR and then from there on individuals have called me.
Now, do you, over the course of time, do you charge money when you review case work and come and testify as a witness?
And is this a money-making enterprise for IAD, you going off and testifying as an expert witness in forensic cases over the last five years?
No. It is a minor proportion of the gross income of our company and it basically covers the expenses of my being gone for someone to replace me.
Now, in terms of preparing for your testimony in this case, did you review the results of the DNA work of the Los Angeles Police Department?
Have you reviewed the collection methods, the sample handling methods and the laboratory procedures of the Los Angeles Police Department?
Have you reviewed what are known as validation studies put together by the Los Angeles Police Department laboratory?
And when you said you visited the Department of Justice, that was in connection with another case?
I visited that laboratory twice. Once in conjunction with another case and once in conjunction with this case.
Now, have you--are you familiar with the testimony of Dennis Fung, Andrea Mazzola, Collin Yamauchi, Gary Sims, Renee Montgomery, Robin Cotton in this case?
Well, I have seen the excerpts here and there on TV, but primarily through transcripts which were provided, and I have reviewed most of those transcripts, although it was impossible to review all of it, I didn't have time, but most of it I have reviewed.
Now, could you please define for the jury the term "Contamination" in a forensic setting, in terms of DNA work?
In terms of DNA work it is quite simply human DNA that is found where it shouldn't be.
Now, in terms of DNA laboratories, would it be useful to break down the kind of contamination that one encounters?
And could you please tell us--could you break those down to us in certain categories?
Certainly. I think a way to look at this is to start all the way back at the beginning at the crime scene and the first type of risk of contamination is going to be called what is called cross-contamination, and as I mentioned, this is human DNA finding its way into a sample where it shouldn't be there, and the--that is as a result of cross-transferring from one space to another physically, and that can happen by mishandling. And the--that is because if you have a sample here with a large amount of DNA and another sample with small amount of DNA, this technique is so exquisitely sensitive that you can transfer without even knowing it frequently a small amount of DNA from item 1 where there was a large amount to item 2.
When you say "Exquisitely sensitive," we have heard that term before. What do you mean by that? It is a scientific term?
Yeah. It simply means that you can find a very, very, very small amount. This technique can theoretically find a single copy of what you are looking for.
Okay. Now, we discussed cross-contamination. Is there something about cross-contamination that is a particular problem in terms of the different kinds contamination you get?
Yes. This--this particular kind of contamination is the one that is the most subversive and that--by that I mean that once you've done that, once you have accidentally transferred from one item to the next, if you were to do the DNA analysis of both items, the DNA analysis doesn't distinguish where that human DNA came from. It is simply going to type what human DNA is there. So that means that if you were to type those two items and you had accidentally done that, those items were--would probably type as the same item, especially, you know, the smaller amount would be most likely overwhelmed by the transferred DNA. So they would type as the same DNA, meaning coming from the same individual, and it wouldn't matter if at that point from that point on it wouldn't matter if this sample that was falsely incorporated--falsely incorporated, if that sample was typed by five, ten, other laboratories or by five or ten different gene systems, it is always going to come up as a match. And the problem with that is there really is no control, unfortunately. There is no way of incorporating into the system a control that says that happened.
KEY QUOTEWell, the second is usually once the DNA or the specimen is transferred to a laboratory, now you can have the same kind of transfer, by the way, cross-transfer can happen anytime that item is manipulated, either in the crime scene, in the laboratory itself, or anytime they are handled, those specimens, all the way through the process that can happen. A second type of contamination, though, that occurs, is the fact that when you are dealing with DNA the samples are fairly dirty samples. In the process of analyzing them you have to add these liquid solutions that contain all of the building blocks for the DNA and the enzyme that is responsible for allowing us to copy it, and the components of that reaction that allows the PCR process to occur.
That is a slightly different concept, and the PCR process I'm sure you are aware of that now, basically allows us to take a small number and copy it, sort of like a molecular Xeroxing up to a very high number. Now, if you do that for the same gene over and over, day after day, with multiple samples, what happens is you have a build-up or can have a build-up of the copies, and when you have a build-up of those copies it is very easy to accidentally get one of those into your reagent or into your reactions, and that is called amplification product carry-over.
Okay. Dr. Gerdes, based on your review of the data in this case, have you formed an opinion as to a reasonable degree of scientific certainty about contamination at the LAPD DNA laboratory?
Your Honor, my method here is that I'm going to elicit the opinions of the doctor and then give the basis of his expert opinion.
Have you an opinion, within a degree of scientific certainly, about contamination at the LAPD laboratory?
I found that the LAPD laboratory has substantial contamination problem that is persistent and substantial.
KEY QUOTEChronic--it is chronic and it is chronic in the sense that it doesn't go away. I can find it month after month and it persists.
Is--as a DNA lab director do you have an opinion about the risk of error due to contamination at the LAPD?
As a molecular biologist and DNA laboratory director, do you have an opinion about the collection, specimen handling and sampling method used by the personnel at the Los Angeles Police Department in this case?
I found that the specimen handling procedures were done in such a manner that it had a tremendous--there was a tremendous risk of the potential of cross-contamination.
Given your views on contamination at LAPD and the sample handling methods that the personnel used, do you have an opinion about the reliability of the results obtained not only by the Los Angeles Police Department, but by the Department of Justice and Cellmark on the samples that have been called the Bundy blood drops, that is, LAPD items 47, 48, 49, 50 and 52?
Dr. Gerdes, have you examined and formed an opinion about the handling of the samples from the Bronco that were collected on June 14th and August 26th in this case?
Let me go back and try it this way: Dr. Gerdes, have you examined the data and the testimony about how the Bundy blood drops, items 47, 48, 49, 50 and 52, were handled in this case?
Have you examined--based on your examination of how those items were handled and your review of the conditions at the L.A. Police Department laboratory, do you have an opinion about the reliability of the results obtained not only by the Los Angeles Police Department, but by the Department of Justice and Cellmark on those items?
Have you reviewed, Dr. Gerdes, the D1S80 results obtained on the Rockingham glove by the Department of Justice?
All right. And have you reviewed the way that that Rockingham glove was handled and sampled by Mr. Yamauchi on the morning of June 14th, 1994?
All right. Before we move on to a discussion of those results, I would like to ask you a series of questions, sir, with the use of a chart, concerning the use of PCR and RFLP technique in the forensic setting and in the medical setting. Your Honor, if I may, I would like to move the chart out here.
Your Honor, I would like to mark this chart as Defense next in order, which I believe is what, 1284?
Now, can DNA technology, that is the RFLP and PCR technique, be reliable and validated for one application but less reliable when transferred to another application?
Yes. That is called technological transfer and any specific or way of doing things, when it is used for a different purpose, for various different purposes, each of those will have their own unique problems and so you have to deal with those problems during that transfer.
Where did the RFLP and PCR technique start? Where were they first developed? In the research setting, the medical setting?
They were--the PCR methodology was developed in a research setting, specifically in the field of molecular biology.
And what was the first application of these techniques? Was it medical or forensics?
Well, it began in the research community and then the medical community was the next area where it was applied and then finally forensics.
All right. What I would like to do is go through some of the differences between medical and research applications of these techniques and forensics. First, on the issue of samples, what are the differences as you see them between samples in the medical setting and samples in the forensic setting?
Well, Dr. Gerdes, do you have familiarity with the kind of samples that are handled in the clinical setting?
And do you have familiarity with the kind of samples that are handled in the forensic case work?
What kind of samples are handled in the medical or research community? Could you describe what they are?
These are aseptically collected sterile samples that are collected from a patient by a trained microbiologist or medical personnel, transported to the laboratory in a sterile container and then handled in a sterile environment, a hood that is a sterile hood.
And in forensics how are, generally speaking, samples what kind of samples are you dealing with?
And have you reviewed the kind of samples that were collected in those cases and where they came from?
They involved various crime scenes. All of them involved, you know, blood, hair, semen found in--in an unsterile condition on carpets, in dirt.
I'm sorry, excuse me. Objection, no foundation. Objection, no foundation, move to strike the answer.
I'm going to sustain the objection. No foundation at this point. It is based on hearsay at this point.
Well, have you reviewed literature with respect to forensic samples and their properties and how they are collected?
And have you seen photographs and examined actual samples from forensic laboratories in the various cases that you have reviewed?
Have you reviewed cases involving mixtures of epithelial and sperm cells, for example?
Now, in terms of the samples that you have reviewed in forensic cases, what are the differences between those kind of samples and the samples that you have encountered in the medical and research setting?
I believe you have just described the differences. Those samples are found in various substrates, none of which are sterile, obviously sterile blood specimens, and in various stages of degradation and different ages and they are obviously not clean samples. They are samples that are definitely dirty and definitely not collected in an ideal manner.
All right. Now, in terms of just the application of the technology and the challenge posed by the samples, which kind of samples, just by their nature, umm, create a higher risk of encountering contamination and erroneous DNA typing; the samples in the medical and research setting or the samples that you've viewed in forensic case work?
Well, obviously if you have a sterile sample that is aeseptically collected, versus a sample where there is absolutely no way of controlling how it is collected or where it is found, the chances of foreign DNA from someone else are going to be much greater in this situation than in this situation, (Indicating).
All right. So would it be fair to say that in terms of risk of contamination error, at least just in terms of the sample, forensics is a greater challenge?
Would it be fair for you then to--if there were a box here, would you check that off with respect to dirty samples?
Sorry to reveal the next check mark here. In terms of sample size, what are the differences between the samples that you encounter in the medical--in the medical area, the clinical area, and the samples that you've viewed in forensic case work?
In the medical area we can pretty much request the sample volume that we need, so sample size is not a problem. You ask for the ideal amount of material you need to do the testing.
Now, in terms of amounts--incidentally, in other words, are some of these DNA tests best performed when you can actually quantitate the amount of DNA?
What are the recommended amounts for the DQ-Alpha PCR technique in terms of the minimum amount of DNA that you would like to have in a sample?
Is there anything in that literature, the user guide, that indicates what the preferred amount is, for example, in terms of minimum size for doing a DQ-Alpha reverse dot blot analysis?
Now, in terms of--so you were getting back to the issue of sample size. You said that in the medical setting you can control the amounts of DNA that is being tested; is that correct?
That's correct. You can ask for an ample size of the original sample. You can purify the DNA and you can quantitate precisely the amount and therefore add the ideal concentration of DNA that is needed for the particular test.
Now, in terms of sample size, in your review of the evidence in this case and in other forensic cases, does the same situation obtain in terms of the availability of sample?
What kind of amounts of samples have you encountered in this case and in other cases as compared to the amounts in the medical and research setting?
In this case and in other cases frequently you have very, very small amounts of DNA and that is basically because you take what you get. You have no option. You have to work with whatever is there. And so frequently that is very, very small amounts, less than what is ideal and less than what is recommended for these kind of tests.
In terms of the risk of contamination and erroneous typing, are there greater risks associated with the kind of small samples that one encounters in forensic case work than in the medical generous sample size in the clinical context?
Sustained. Doctor, let me ask you to take the longer pointer and step back one step so that the court reporter can hear what you are saying.
Does sample size have anything to do with the problem of contamination and erroneous typing?
Yes. Sample size, if it is too small, there is an increased risk of contamination, there is an increased risk that you will miss some of the DNA, that is, something is there and you don't find it.
All right. And in your judgment did the minuscule size--what does the term "Minuscule" mean?
Okay. Is that the kind of sample you are talking about that is encountered in forensic case work?
All right. Are--now, does the minuscule sample size encountered in forensic case work, what implication does that have for you as far as you are concerned in terms of the risk of contamination and error as compared to the clinical setting.
All right. Now, in the clinical context, in terms of mixtures, what kind of sample do you get there as opposed to forensic case work?
Well, in the clinical setting for the vast majority of the types of tests we do we are concerned with a specimen or a sample that comes from one individual and so it is very rare that we will work with something that is a mixture.
In the forensic context and in this case what kind of samples are often encountered?
Most of the times in a forensic case obviously you don't--you are finding something at a crime scene, so you have no way of knowing whether that came from only one individual, one contributor, two contributors, three contributors. You have no way of really knowing how many people that might have actually come from and that--that is--that means that you don't--you don't know if you have a mixture. And then when you do the analysis, frequently it is found to be a mixture.
And in terms of the risk of contamination and error, in which application of DNA techniques is the risk of contamination and error greater just because in the nature of that sample?
It is much greater in the forensic setting. It is very, very difficult. It is a difficult task to deal with these mixtures because the genetic systems are more precise and can be interpreted more--more cleanly if you know you are only working with one person.
Now, in terms of handling of samples within a laboratory, could you compare for us which of the applications has more or less handling of samples within the laboratory?
All right. Are you familiar with the specimen handling techniques in clinical laboratories?
Have you examined the specimen handling techniques used by the Los Angeles Police Department in this case?
Are you familiar with the techniques used by Cellmark and the Department of Justice?
Are you familiar with the specimen handling techniques used by the other laboratories that you visited?
All right. Which laboratory does more or less handling of the samples in the course of doing DNA testing?
There is much more handling in the forensic setting. Those specimens are--because they are found at a crime scene, and in a non-sterile situation, they have to be handled, itemized, packaged, transported to the lab and then sorted out so that they--they can be analyzed--reserving perhaps some for future analysis by both the Defense and the Prosecution in the case and then they have to be handled from a non-sterile state from the very beginning, because they are found that way. In a clinical lab we can work with one specimen in a sterile drawn tube that was transported to the lab, immediately goes right into the testing process and it is not handled for anything other than that.
Now, in terms of the risk of contamination and error, where is it greater, in the situation where there is less handling of the sample or in the situation where--the forensic situation where the samples have to be taken from the scene, dried, unpackaged, dried, packaged again, opened again, cut up again, et cetera?
Now, in this connection, in the clinical area do you have occasion to do what is known as split samples for independent testing with other laboratories?
All right. When you are dealing with sensitive PCR kind of testing, how is a sample split or put aside for independent testing by another laboratory?
Well, the ideal situation would be at the time that the specimen is collected, you would collect two tubes and one would be transported directly to laboratory one and another is transported directly to laboratory two. There is no possible contact between those two labs.
Is the idea--in terms of the handling when you are doing a split for an independent laboratory analysis, is the idea to minimize the exposure or handling of that sample in laboratory one?
Well, as I explained earlier this problem of cross-contamination, if that becomes an issue, then if you have designed the entire way in which the sample was tested in such a way that there is--it is impossible, absolutely impossible for laboratory one, their specimen to have come in contact with laboratory two or vice versa, then by the very design of the way you set it up, it eliminates that whole argument.
All right. Now, in terms then again of minimal handling and multiple handling, is it your testimony there is a higher risk of contamination and error in the forensic application?
I would like to turn to the question of error rates. Your Honor, I think it will go faster here, I can finish this board and then take a break. Would that be fair? Do you want to break right now? Okay.
All right. Ladies and gentlemen, we are going to take our mid-morning break at this time. Please remember all of my admonitions to you. We will stand in recess for fifteen minutes.
I found that the LAPD laboratory has substantial contamination problem that is persistent and substantial.
Chronic--it is chronic in the sense that it doesn't go away. I can find it month after month and it persists.
This particular kind of contamination is the one that is the most subversive and that--by that I mean that once you've done that, once you have accidentally transferred from one item to the next, if you were to do the DNA analysis of both items, the DNA analysis doesn't distinguish where that human DNA came from.
Contamination is a problem in the development of any PCR technique.