All right. Thank you, ladies and gentlemen. Please be seated. Dr. Cotton, would you resume the witness stand, please.
Robin Cotton, the witness on the stand at the time of the noon recess, resumed the stand and testified further as follows:
The record should reflect we have been rejoined by all the members of our jury. Good afternoon, ladies and gentlemen.
THE JURY: Good afternoon.
Dr. Robin Cotton is again on the witness stand undergoing direct examination by Mr. Clarke. Good afternoon, Dr. Cotton.
Doctor, you are reminded you are still under oath. And Mr. Clarke, you may continue with your direct examination.
Thank you, your Honor. Good afternoon, ladies and gentlemen.
THE JURY: Good afternoon.
DIRECT EXAMINATION (RESUMED) BY MR. CLARKE
Dr. Cotton, you spoke just before the lunch break about the use of cells and I believe you briefly described what their purpose is. Could you state again why controls are used in testing?
In general you are using controls to help ensure at the end of the analysis that the steps worked as they should, that is, an example of that would be you have a type for a PCR analysis and you've typed that sample many times and so you type that sample along with your evidence samples and you make sure that the type that is expected from this one sample you've typed many times comes out as it should. If it doesn't, it tells you that something could have gone wrong during the analysis procedure.
As far as RFLP testing and the use of controls, when you--if I ask you later to examine and describe an autorad or a series of autorads, will you be able to point out the control on that autorad?
Then let's turn to PCR typing and the use of controls. Do they play the same or in any manner a different role in PCR typing than they do in RFLP typing?
There is one of the controls that is used in PCR that basically plays the same role as the controls in RFLP and there are two additional controls that are done that sort of play slightly different roles in the PCR procedure.
What role does--does the use of controls have in this PCR typing process? Why do you use them?
You use them to use one known sample to ensure that the procedure worked as it should, and you use two different negative controls, that is, controls that do not have any DNA in them, and they--one of them starts at the very beginning of the procedure and then one of them starts at the point that you set up the amplification, and they are in there to control that in your handling of the evidence and known samples that you didn't add any DNA inadvertently in the processing for the PCR. And there is actually one other type of control that is done with PCR, but may not be done in every instance, and that is if you have a, umm, say, a stain on a garment, you might take an unstained portion of that garment and have that go through the process also. The interpretation of that control, should you get something, may be somewhat difficult, and if you don't get anything, then it just says you didn't have anything in this one area that you tested.
All right. The first type of control that you described was a control with a known type of DNA in it for PCR typing?
And then you also described and you used the term "negative controls." Does the negative control name come from the fact that there is no DNA in them?
That's right. The known sample that you are typing is called a positive control. That is, you are putting DNA in there and you know what that result should be. The negative control you are purposefully starting with a blank tube, adding your PCR reagents, but no DNA, and therefore, since you are not adding any DNA, you shouldn't get any result.
Well, there is a third type in our lab that is called a reagent blank control. That control is started at the time you are putting your evidence into the tube. You are carrying alongside of that a blank tube. So let's say we have tube 1 and tube no. 2 and in one you are putting your evidence. In tube no. 2 you are not putting anything in there, but then in the process, for example, of doing the DNA extraction, you are adding some things to your evidence so you are also adding them into the empty tube, so it is a way to make sure that everything that you added to your sample did not have any additional DNA in it.
All right. Dr. Cotton, what I'm going to ask you to do, with the Court's permission, is to on a single piece of drawing paper is to describe or list these controls used in PCR typing.
Dr. Cotton, if you would, could you label this particular piece of paper "PCR controls."
And I believe that you had described that the first control was a control with a known type of DNA in it?
Positive control contains a known DNA sample that has been typed many times so the type for this known sample is--is known, so you have a known DNA sample. You carry that, that is set up at the point the amplification is set up, and it is carried through the rest of the typing procedure. If the types in that known sample do not come out as they should, it would be an indication that something had gone wrong in that analysis step--in the series of steps that you have used.
In other words, you know what the type of that positive control is and if you don't detect that type at the actual portion of the test where you determine types, then you know something has gone wrong?
There is really at least two and possibly a third type, all of which could be considered to be a negative control, but we give them different names, so that we don't get confused.
Okay. Then you have listed under "negative control"--there is then two versions of a negative control?
Well, it depends if you want to call it a substrate control. That is a version of a negative control also.
--ignoring that for the moment, could you describe the other two types of negative controls used in the test?
Okay. One of them we are just going to call the negative control and that is set up when the amplification is set up, and the same is true of the positive control, it is set up at the time the amplification is set up. And what I mean by that is that you have extracted your DNA and now you are carrying it into a separate area and you are putting it in a tube and all the--and the PCR mix, the polymerase and the primers and so forth. This negative control is set up at that time and this positive control is set up at that time and this negative control has everything added to it that all the other samples do, except there is no DNA in there at all.
What do you mean when you say it is set up at the same time? What does that term mean?
Simply that you are putting the things you need out on the bench so that you can work with them and you are physically going through the process of taking your tube for sample no. 1, putting in the PCR mix, putting in the DNA. You actually put some oil in these samples also, and then setting that tube aside and going on to the next one.
The PCR components themselves, the mix that has it in the primers and the enzyme and the A's, T's, G's and C's, that could possibly be contaminated with DNA if it were not handled properly, so this is--all of these negative controls are a way to make sure that everything you are adding to the sample is free of any extraneous DNA.
What happens in the typing process if you determine that in your negative control, for instance, are types that shouldn't be there?
Generally, and I'm saying generally because there may be an occasional exception in a laboratory to this, but generally if your negative control comes out with a type, you would disregard all the results for that test and go back and repeat the test.
It consists of everything that was added to the evidence from the beginning of the analysis. If you break the analysis down into DNA extraction and then go up to amplification, in both those procedures you are adding things to your evidence samples or to your known samples. So this control makes sure that when you add things to the PCR set-up, those reagents--those components don't have DNA. And the reagent blank control does the same thing, but goes back as far as the DNA extraction and let's you assess whether or not in adding things to the evidence to perform the DNA extraction, that you are not inadvertently adding some DNA in there.
As far as inadvertently adding DNA, again, how does this control perform that process?
Let's say you have a tube in front of you and you are beginning to do your DNA extraction and you are adding some solution, that is a chemical solution, it might have salt, it depends on how you are going to do your DNA extraction, you want to make sure that that solution that you are adding hasn't any DNA in it. So everything that you add--I don't know how else to say it--everything that you add to the evidence gets added to this Bronco tube, so at the end, if you have DNA in this blank tube, that tells you that you would have been the--the same things that got added to that blank tube also got added to the evidence. It tells you you might have inadvertently added some DNA containing cells to the evidence.
And if you see results in this negative control, or you actually see types, what does that tell you?
If you saw a full blown type, you would certainly declare the results of your analysis inconclusive. There--there--for most instances, if you saw something in the reagent blank, you would declare your results inconclusive. I can think of a few examples of when you wouldn't do that or you might consider not doing that, but in general that would be what you would do.
Yes. That each one of these controls is an alert to you of a problem that could have occurred and it helps you sort out where that problem could have occurred.
KEY QUOTEAnd I also believe you said there was a fourth control as well or actually a third type of control, but a fourth control?
On the typing strips themselves there is a dot which needs to appear in order to assure you that you had enough amplified DNA to get a reliable result.
As far as these dots, do they alert you to the potential of problems in this typing process, and I'm referring to the dots that you just described?
They don't alert you to a problem. They alert you to the fact that they say you had enough DNA in your sample, that is, you had enough amplified DNA in your sample and the results on this strip are reliable because you can see this control dot. If you don't see the control dot, it may mean that you are missing some types. You may see some types, but you can't be assured that you are seeing every type that could be there.
As far as these controls--or that control dot, was that in fact present on the typing strips that were passed around to the jury earlier, although bearing in mind that those strips had not been developed?
Yes. The control dot on the strips that were typed (Sic) around is designated with an "s" and you wouldn't have seen it because they haven't been developed, but where there was a designation for an "s." That is where the control dot would be.
Your Honor, if we may, I would like to ask the witness in this subject area some brief questions, and the exhibit is People's 252, one of the large charts.
No. Actually, I think, Dr. Cotton, if you could just stand by and not get hit by the chart.
With regard to this chart, Dr. Cotton, People's exhibit 252, the strips that we see on the left-hand side of this diagram, those are strips that are used to type what genetic marker?
And on those strips is there a specific location where the control dot is that I just described?
It is just to the right--my right of the C here, (Indicating), so this dot that is between the C and the no. 1.1, this is the control dot.
And is that the dot that then performs that function or role that you just described when you were writing on the diagram, People's exhibit 254?
There is and it has a designation as an s dot, but in fact it is made up of the same components and it performs exactly the same function as the C dot.
All right. Very good. Thank you. Dr. Cotton, you also described or used the term "unstained control." Was it?
It would be a--best example I can think of is a stain on a garment would be a portion of that garment that did not have any apparent stain which you could then type and use that to help you interpret your results on the stained portion of the garment.
In what way? How does that assist in the interpretation of any results from a stained portion?
Well, it may assist in that that--the control portion may not have any type at all and that would just be a general indication that the garment itself--usually the control is taken very near the stain so I'm not thinking about taking a control on one shoulder and then looking at other stain on another shoulder. So you are taking the control near where the stain is and you are saying, well, I don't have any additional DNA besides what I'm seeing and therefore what I'm seeing from the stain is probably all the DNA that is there. I mean, the other obvious result is that you've got a type from your control section and that might mean, for example, suppose someone had worn a shirt for a very long time, you know, a week or something. You might actually pick up some of that person's type who had worn the shirt for a week on a control section. You might see that type reflected in a stained section as well, so it would just be information on the condition of the surrounding area of the stain.
Why would you be able to see a person's type on a garment that had been worn for some time?
Because you may have skin cells that if you have worn a garment for a really long time may have adhered to the fabric and you may have a sufficient number that you would actually see a type. Now, I haven't done an experiment on this but I have just used this as an example.
All right. As far as these unstained or substrate controls, as you have just described them, do they play any role in determining whether or not contamination of a sample may have occurred?
It doesn't--well, actually, yes, it would help you to determine that as well. If you picked up a type on the unstained portion, the other explanation, other than what--either that type existed on that unstained portion at the time it was collected or it had been deposited on there somewhere during the processing. And there is no way you could be able to distinguish which of those two scenarios had happened. It would just alert you to either the thing had DNA on it when you started, or some extraneous DNA may have gotten on it during the processing and you couldn't tell the difference.
How often do you receive unstained or substrate controls in case work at cellmark?
I don't know how to give you an exact figure. We receive them some of the time. Most of the time we do not.
As far as all of these controls that you have described, do they all represent different versions of basically lights that can be lit or alerts to you about the potential for problems?
Now, turning in particular to the strips, and these are these PCR-type strips--and I believe just a few moments ago you pointed to a DQ-alpha typing strip and then you also--or we also showed to the jury a polymarker typing strip; is that right?
These results, and I believe you have already described this, are actually read visually, that is, a person looking at them and deciding where there are positive results and where there aren't; is that right?
Blue dots. Does one person simply read those results in the laboratory to determine what the types are that are present?
Well, not in our laboratory, and I can't speak for every laboratory. Every laboratory that does this does not have exactly the identical procedure. In our laboratory the evidence samples are read by two individuals. If you are doing a known sample, that sample may only be read by--only needs to be read by one person, but any evidence sample gets read by two people.
As far as these results themselves, are they maintained--do the strips still exist, for instance, if you want to look at a case a day later, a week later, a year later and so forth?
The strips still exist and you could go look at them, but they are not the best permanent record of the results because the blue color in the dots can fade over time.
What steps, if any, do you take to record these results at the time that they are read so that they can be looked at later?
There is two things that are done. The strips are read visually by two different analysts and those readings are recorded on paper and the strips are photographed and those photographs are maintained in the case file.
They are provided--there are two original photos that are taken. Generally we maintain one and the other one is provided to the Court or to the Defense or to the Prosecution, whoever is in need of that copy.
Does that allow those results then to be reviewed at a later time by any of those people you have just described?
Now, I would like to turn our attention, Dr. Cotton, to an area frequently referred to as proficiency testing. What is proficiency testing?
Proficiency testing is generally the receipt of samples in a laboratory where the samples are sent from an agency or an organization who is engaged in providing proficiency tests. And it is just that, it is sort of a test, the agency knows what the answers should be, they are sending samples to the laboratory and the laboratory in general is aware that these are proficiency test samples, does the analysis, reports the results back to the agency and then the agency, which may also send these tests out to many other laboratories, will compile the results and send a report out.
It is to enable you to make an unbiased judgment about how your lab--how well your laboratory is performing, because you have an opportunity to do a set of samples where someone else knows what the answer should be and also to compare how you did with how other laboratories receiving equivalent samples would do or did.
Incidentally, is cellmark, and you described yesterday cellmark in the United Kingdom, is it involved in providing proficiency samples to any laboratories?
Cellmark in the United Kingdom has a proficiency test program where they do provide proficiency samples to other laboratories and we receive them and many other labs in the United States do as well.
Everyone that is involved in doing any kind of analysis for forensic or paternity case work takes proficiency tests during the year and generally each analyst is required to perform two per year.
It includes myself and the other Ph.D. staff, since we are involved in the analysis of the case work results.
You touched briefly yesterday on the fact that there are other individuals in the laboratory who perform the actual bench work; is that right?
Would actually be pouring in the reagent, manipulating the steps necessary in the tests and then ultimately producing the product that is eventually read and interpreted?
In this case, and we will return to it a little bit more a little later, in this case who were those individuals who actually performed this work in this case?
With respect to both of those individuals, have they participated in proficiency testing as well while at cellmark?
These proficiency tests, can you describe in a little bit more detail about how they are set up and in what form they are sent to the laboratory for purposes of testing?
I can tell you how we receive them. I don't know very much about how they are set up, since I am not involved in doing that. We generally will receive the samples. Umm, they are usually shipped at room temperature, and for forensic samples, they are made to be similar to case samples, so they are usually bloodstains and the knowns are usually bloodstains on Cotton cloth, and the evidence samples may be bloodstains or semen stains or some mixture. And generally a proficiency test will consist of three or four samples which would be the typical number of samples that might be in one case, at least that is for our laboratory, typically for a single case it will be maybe average four samples. And they are received by our quality assurance coordinator and then she hands them out to whoever is next in line to do a set of proficiency samples.
As far as these samples, when they are sent to you and if, let's assume you are an analyst actually determining what the results from typing of these samples are, are you informed ahead of time of what the results are?
Are you therefore required to complete the test, report the result and then later you find out if you did it correctly?
Now, how often are these tests--and I believe you touched on this that--you have already answered this--how often are members of your laboratory required to take these tests?
Are there any organizations that set recommended frequencies for taking tests like this?
There are two organizations who have guidelines for laboratories that are engaged in DNA analysis, and both of those organizations, in regards to proficiency tests, recommend that each analyst or each person involved in case work do two tests per year at a minimum.
One organization carries the acronym Twgdam, T-W-G-D-A-M, which stands for the technical working group on DNA analysis method and is sponsored by the FBI and consists of crime laboratories from around the United States and members of the FBI laboratory.
Does that group also issue guidelines on a range of areas involved in DNA testing?
They have issued guidelines on conducting DNA testing, staff for DNA testing, and quality assurance programs for laboratories engaged in DNA testing.
The second organization is Asclad lab, A-S--again it is an another acronym name. Asclad, that is the American Society of Crime Laboratory Directors, Laboratory Accreditation Board.
If this jury had previously heard testimony about Asclad, would that be the same organization?
The first proficiency test that I am aware of that cellmark took was actually received in late 1987, so it would have been received about the same time, in the same time range, as we started doing case work.
Do you, as part of the business at cellmark, compile information about how the laboratory has performed in these proficiency tests since they were begun?
As far as the taking of these tests, these proficiency tests, and the results, can you describe for us, beginning back when proficiency started, how the laboratory has performed?
I can. When--let me preface my remarks by a very brief explanation that proficiency tests have been available all during the time that DNA testing has been done, but early on proficiency testing specifically designed for DNA testing labs was not available and the tests were geared more towards serology analysis. In 1988, or actually late 1987, there was a proficiency test put together by the California association of crime laboratory directors which cellmark agreed to participate in. That test was not a typical proficiency test as I have just described one to you, and the reason is that that test consisted of 49 samples. There were no designated known samples and unknown samples. So what I'm really saying is that that proficiency test did not resemble a regular case in terms of the number of samples and the fact that in a normal case you have known samples and unknown samples. Apart from that, the samples were forensic type samples, stains and so forth. In that proficiency test we provided results back to the Cacld, which is the abbreviation for California Association of Crime Laboratory Directors, and we later found out that we had one error in that proficiency test, that is, we matched a sample to another sample and that match was incorrect.
With regard to those results--incidentally, were the remainder of the results--how did you do on those?
The remainder of the matches that we got were okay. There are some samples that we didn't get any DNA from, there were some samples that we didn't get a pattern from that was usable, so I'm not implying the rest of the results were perfect, but there with no other incorrect matches in the results, other than the one.
As far as this--this error, as you have described it, do you just take that error into account and just continue in your work or do you take any action as a result of that?
I certainly wouldn't want to just continue working without attempting to figure out what had caused such a significant error. So the procedure that I followed was the people that had worked on the test went back and examined all of their records, all of the tubes that they had kept during the analysis of that test, and they were able--and I'm saying "they"--although I was there at the time, I didn't participate directly in figuring this out--they were able to determine whether the error had occurred and what had happened to cause that error and that was helpful then in making some changes in our procedure to improve the procedure.
Well, there were some changes made in--made to address the error. You sort of have to know what the error was for to it make a lot of sense, but there were changes in how the tubes were labeled so that--because part of the problem was that--an analyst couldn't read the labels well on the tube, and there was also a piece of equipment purchased to help us avoid the situation that had caused the error.
All right. In terms of proficiency tests taken after that time, can you describe the performance of the laboratory.
So then comes along 1989. Now, actually without the document in front of me, there probably--there may have been a few other tests in 1988, besides this large one, and as far as those tests went, there was nothing wrong with Cellmark's performance. In 1989 there were tests taken and for the most part there was no problems with Cellmark's results, but in 1989 we again accepted a sample sent from CACLD. This sample set consisted of 50 samples, was designed the same way the first one was and cellmark had an additional error in 1989, an incorrect match in that 50-sample set.
As a result of that error, was any further review undertaken or was this again a situation--not again, but was this a situation in which you just continued on with case work?
As a result of that error additional review was undertaken. It took quite a long time to do that review because there was a lot of material to look at. The error--the specific error was not able to be determined. We could narrow it down to a particular two samples between which the error had occurred and we knew the step at which the error had occurred, but exactly how it occurred we can't tell--I can't tell you and I was part of this analysis. To--we went in and looked at our procedure and the adjustment that we made to our procedure as a result of this test was one that I've already talked about, and that was the mandate in the procedure that you do not do the DNA extraction for evidence and known sample at the same time in the same place. That is, you do the evidence, you put that away, and then you do the known samples, because the most--and so this was a situation where DNA from one sample had contaminated another, and obviously the most critical contamination that you could have would be from a known sample to an evidence sample. And so to avoid that, those samples are not extracted at the same time and that was the adjustment that we made in our procedure as a result of that error in 1989.
Are changes or improvements in procedure one of the goals of proficiency testing or one of the benefits?
Well, they are one of the benefits. It does give you a window on your work that you wouldn't have if you weren't taking proficiency testing.
That's right. Now, again, there would have been some other proficiency tests taken during 1989 that would be similar to the ones--the typical ones that I described before where you get three or four samples, and there were no false matches or false exclusions in any of the other tests in 1989.
From 1990 to the present time we have continued to take proficiency tests. They are all now--in fact, the proficiency tests are much better now than they were back then because they are designed for DNA analysis laboratories specifically, and as I said, they generally consist of three or four samples, and since this time there have been no further errors in proficiency tests in terms of incorrect matches or incorrect exclusions in our proficiency testing.
During that time period from 1990 through 1995, approximately how many different tests are we talking about? Can you estimate that?
You know, that is all listed in a document that I know you have and I have a copy of, but it is not down here with me. Let's estimate it this way: We have had for the most part, during these years, six or seven analysts and they have taken at least two tests per year, occasionally more than that. So you are doing about, say, fourteen tests per year at a minimum.
We don't get a separate test, because the design of the test is that you do it as if it was a regular case, so we are participating in the test in our normal role for doing case work, so we don't get additional tests that are directed just toward us.
Well, we hold a license to handle radioactivity. We hold a license to transport--it is a clinical laboratory--under the clinical laboratory improvement act, to--basically that allows us to transport samples across state lines and there is an inspection associated with that license. We have a license in the State of Maryland to do molecular biology techniques. There is an inspection associated with that license. Umm, we have a few other odd licenses that aren't very well--
Is there any certification or accreditation process involving DNA testing laboratories in this case?
There are actually three programs of which we participate in two. One of them is sponsored by the American association of blood banks, and I mentioned that I think yesterday, and it is an accreditation for doing paternity testing and you can get accredited using--for like HLA testing or ABO testing. Since we only do DNA testing, our accreditation is in that area only.
Are there any other organizations who participate in accrediting or certifying DNA laboratories?
There is another organization that is--accredits laboratories for paternity testing and it is a very similar program to that of the American association of blood banks and we aren't currently participating that program. And there is a program sponsored by Asclad that is the American society of crime laboratory directors, for accreditation of forensic laboratories doing DNA analysis and we--
As far as that accreditation, to your knowledge were you the first private laboratory accredited by Asclad?
Yes. We--there had been many--or I don't know about many, but 20 some DNA laboratories accredited by Asclad and these were all state labs or local labs or some type of government lab. So we were the first private for business laboratory that Asclad accredited.
Now, in that process of accreditation by the American society of crime laboratory directors, what did that entail? What did it take to obtain that?
It was preparation. Involved about six months of work off and on. We submitted to them answers to a very long questionnaire. We submitted documentation of our procedures for quality assurance. We submitted documentation of our testing procedures in the laboratory. And I don't know, we submitted--you know, it is one of those things where you send in three copies and stuff like that. And then we were given an inspection date and we had an inspection from Asclad inspectors. We had three inspectors in our laboratory for three days, and they looked at individual cases, they looked at the laboratory facility, they interviewed all of the laboratory staff involved in forensic cases, and then they did an evaluation.
As a result of that evaluation we received an accreditation by that organization this past September.
As far as this accreditation process, did it include, for instance, the laboratory's use of RFLP typing in forensic cases?
You've also mentioned an organization that you have described as Twgdam or Twgdam. Does that organization--and I believe you mentioned earlier--does that organization produce guidelines for DNA typing in forensic cases?
Can you tell us a little bit--you described some basic areas that those guidelines describe. Can you tell us in a little bit more detail how this covers forensic DNA typing?
It is--it is very similar, although not identical, to the guidelines that you have to meet for Asclad. The guidelines cover what kind of education and training your staff should have, what kind of quality assurance program you should have, what kind of documentation of the work that you do that you should keep. There are some specifications in there about how the DNA testing should be done, guidelines on general aspects of doing the DNA testing, and there are some guidelines as to how the results should be reported. There is then a separate document written by the same organization that covers in more detail what would be--what a good quality assurance program would encompass.
As far as these guidelines from Twgdam, does cellmark follow those guidelines in its forensic case work?
Incidentally, I know you described Twgdam as being sponsored by the FBI; is that right?
It is made up of a lot of crime labs and my understanding is that it is sponsored by the FBI. I don't--we are not a participant--we are not a participant in Twgdam so you know, I'm not positive that that is correct.
In terms of your human identification or forensic case work at cellmark, are you asked to perform testing exclusively by Prosecuting agencies?
We may be asked to do case work by Defense--a Defense attorney, and in terms of Prosecuting agencies, I guess you are including both investigators and attorneys, so we--we work for whoever is interested in sending us a case.
In other words, by your last answer, you were referring to being asked to perform testing by a Prosecutor's office like the Los Angeles District Attorney's office in this case?
Yes. We might receive samples from a District Attorney's office. We might receive samples sent to us by a crime lab or we might receive samples from an investigator.
Far as your testing, is it the case that in some instances you obtain test results and after that criminal charges are filed in cases?
Is it also the case that following your testing in case work it may be that criminal charges already filed are dismissed?
Is it also the case that after obtaining results in your case work that in fact people may be released from prison as a result of those case work results?
Thank you, your Honor. And lastly, Dr. Cotton, has your laboratory retained results in cases that may lead to exonerations, that is, charges actually being dismissed?
Now, as far as the laboratory itself, do you allow individuals not a part of the laboratory to visit your laboratory?
It--there is two general groups of folks that that might include. We might be asked to have a--suppose we are doing a case for the Prosecution. We might be asked that a Defense expert, that is, a scientist working with the Defense, to be allowed to come and view the testing while it is being done, and we do allow that. We have a set of guidelines that everybody needs to--we feel that everybody needs to agree to, and if everybody agrees to those guidelines, an expert for the Defense is allowed into the lab to watch testing. And we may have the reverse situation. We may have a case that has been done for either the Prosecution or the Defense and another expert working for that same group may wish to come--who may then come to Court to say, yes, I think this testing is okay, or no, I don't, but usually it is yes, I do think it is okay. That expert may come to the lab, look at the laboratory, discuss laboratory procedures, ask laboratory staff questions or something to become familiar with how work is done in our lab.
Now, you described the fact that there are some guidelines in place about these visits?
Umm, as far as watching testing, the most important thing that they include is that the visitor will only be allowed in the laboratory when testing on that specific case is ongoing and that is there are many times during the testing where you do something and then you have to wait maybe four hours before you can do the next thing, so that the visitor isn't allowed in the lab during that four-hour waiting period, they are asked to wait somewhere else. And the other really important criteria is that they are not allowed to ask questions of the analyst or talk to the analyst while the analyst is working, and that is really to make sure that the analyst is allowed to give their full attention to the samples that are in front of them and they are not distracted by somebody saying "why are you doing that" or "what step is this" or something like that.
They are not enormously common. We probably have Defense experts in three or four times a year maybe, probably not more than that.
There were two visits. The first was a visit from Dr. Edward Blake and Dr. Henry Lee, and they came to the lab and--and witnessed and took part in, actually, the division of some of the samples. The samples were small blood-stained swatches. Ten percent of those samples was to be set aside for future testing, and Dr. Blake actually took the cuttings that were set aside for future tests.
That was actually an exception to our guidelines because normally we won't let--
KEY QUOTEeach one of these controls is an alert to you of a problem that could have occurred and it helps you sort out where that problem could have occurred.
we had one error in that proficiency test, that is, we matched a sample to another sample and that match was incorrect.
since this time there have been no further errors in proficiency tests in terms of incorrect matches or incorrect exclusions in our proficiency testing.
we work for whoever is interested in sending us a case.
That was actually an exception to our guidelines because normally we won't let--