Where did the EDTA come from?

Factual Questions
1

I have been reading about the OJ Simpson murder case, and I have yet to get one matter resolved.

During the criminal trial in 1995, the defense claimed that two specimens of blood evidence were planted. One was a smear of blood on a gate at the crime scene. The other was a spot of blood on some socks found in OJ’s bedroom.

During tests of the blood, a compound called EDTA was detected. Since EDTA is used as a preservative in stored blood, the defense contended that the two specimens were taken from stored blood and planted.

Where did the EDTA come from?

The most recent and authoritative answer I have comes from FBI toxicologist Roger Martz and bio-molecular expert Dr. Terry Lee. The FBI did not want Roger Martz testifying for civil litigation, but Dr. Terry Lee testified during the civil trial. They shared theories as to the source of the EDTA. It was leftover residue from preceding tests. That is, the testing equipment was contaminated.

The civil trial was in 1997, and I have been hoping for more recent confirmation. Has there been a consensus of opinion among experts that Martz and Lee were correct? Has there been a more authoritative answer since the civil trial?

2

From the real killers?

Are you sure EDTA is used as a blood preservative? It sounds unlikely to me. It is pretty reactive stuff. It is a chelating agent, that sucks up metal ions. That it might be used in some forensic tests of blood, as Martz’ and Lee’s theory implies, seems far more likely.

3

EDTA is used to prevent blood clotting (by chelating Calcium ions). It is commonly used in collection tubes (Heparin is also commonly used).

In the OJ case, the implication by the defense is that the blood found was previously collected and then planted.

4

Too late to edit, but here’s a link describing collection tubes. EDTA tubes have purple caps. You could also just add EDTA to a plain tube.

5

Your reply is useless. First, there is no question about the identity of the “killers.” There were no killers, there was only a killer. OJ Simpson. Second, there is no question about EDTA’s use as a blood preservative. It is so used (or at least it was at the time of the killings). As a subsequent poster noted, storage tubes that are lined with EDTA have purple caps.

The question that has yet to be resolved with reasonable certainty–at least in my mind–is why the EDTA was detected during tests of the two specimens of blood evidence. That is, where did it come from? FBI toxicologist Roger Martz and bio-molecular expert Dr. Terry Lee said it came from contaminated testing equipment. But there has been argument against that theory, and I would like to know if there has been a firm resolution of the issue.
:slight_smile:

6

Not exactly to the point of the OP, but I watched virtually every minute of that trial, as I was unemployed at the time. O.J. Simpson was the killer. Period. There is absolutely NO doubt, reasonable or otherwise.

A lot of evidence that was revealed to the public and the TV audience was kept from the jury because of defense tactics. Some jurors said afterwards that if they had been able to see all the evidence, they definitely would have convicted him.

That particular leopard has not changed his spots either.

7

I think you’ve been whooshed. njtt’s remark was pretty clearly meant as a joke.

8

Thank you, Colibri and ThelmLou for your posts. And I apologize to njtt if he/she was being ironic. :smack:

I hope my post stays near the top. My question has yet to be answered, and I am genuinely interested in a good answer.

Why was EDTA detected in the tests of blood evidence from the gate and the socks? Where did that EDTA come from? Does everyone now agree with Roger Martz and with Dr. Terry Lee’s testimony, regarding contaminated testing equipment? :cool:

9

If you’ve been unable to find an update via Googling, then I suspect the answer is that there simply is no further information.

10

Why couldn’t it have been planted evidence? We seem to have an unfairly excluded middle here. OJ Simpson could have been both framed and guilty. It’s not simply one or the other.

11

Maybe the real killers were being treated for lead poisoning.

12

It really could not have been planted, but a full answer would bore you. I’ll just focus briefly on the blood on the rear gate. It contained OJ Simpson’s blood. As did drops of blood along the left side of the walkway leading to the gate. (It was not an amazing coincidence that Simpson had a cut left hand, on the same night as the killings. A cut that was consistent with the drops along the walkway.)

Now, if you were a reasonable person, I have already said enough to make you skeptical about blood planting. But in this case, the defense had an agenda other than reason. So I’ll say more.

To plant the blood, Simpson’s blood would be needed. Yet, the police–the alleged planters–did not have any of Simpson’s blood until 3:30 pm, on the day after the killings. That blood was extracted from Simpson and given to Detective Vannatter at Parker Center police headquarters in downtown L.A…

Multiple detectives saw the blood drops and the blood on the gate during the preceding night. Could they all have lied about seeing the blood? Not in this universe, but it IS something the defense might allege. Even if they did lie, the walkway crime scene was closed at 3:45 pm. By which time the criminalists had gathered all specimens of blood evidence.

Detective Vannatter did not leave the Parker Center until 4:30 pm. He had the purple-capped vial of Simpson’s blood with him. He delivered it to criminalist Dennis Fung at Simpson’s Rockingham estate, at 5:20 pm.

Even if Detective Vannatter had left the Parker Center immediately after getting the blood, he could not have driven to the walkway crime scene and planted the blood for the criminalists to collect before 3:45 pm. Not even if the approx 15 miles of intervening freeways and streets had been vacant. Even if he were transporter-beamed up to a starship and then transported down to the crime scene, it’s doubtful if he could have meticulously deposited blood drops in the exact spots necessary to be consistent with Simpson’s cut left hand. Besides, the criminalists would have seen him.

And let’s not forget about specimens of Simpson’s blood found on and in the white Bronco and at various spots at Simpson’s estate.

Even if invisible men and starships managed to plant Simpson’s blood, that still does not explain the EDTA. When the two evidence specimens were tested, the EDTA that was detected was inconsistent with the amount of EDTA in stored blood. By an order of magnitude, the amount detected with the evidence was MUCH less than any amount found in stored blood. That is what led FBI toxicologist Roger Martz and City of Hope bio-molecular expert Dr. Terry Lee to say the EDTA was residue left over from a preceding test.

Ferret Herder’s reply: “If you’ve been unable to find an update via Googling, then I suspect the answer is that there simply is no further information.”

I do not believe that. After all, Martz and Dr. Lee were only theorizing. And that was in 1997. I think by now, someone would have a more definitive, certain answer as to why EDTA was detected when the evidence was tested. :frowning:

13

There’s no question that the blood was Simpson’s, not some other killer’s. The blood evidence had Simpson’s DNA. The question is why EDTA was detected during tests of the blood evidence. It was a question that caused the defense to make allegations that the blood was planted. :cool:

14

If that were indeed the case, wouldn’t it have been written down somewhere by now?

15

Ye. I was implying that he had been treated for lead poisoning. It was a joke. Sorry, that wasn’t clear.

16

Was the test and equipment specified is this testimony? It would help to know what they did and what was used (and what other, different tests were run on the equipment).

I’ve never done forensic testing of blood myself, but I have a lot of lab experience and routinely have worked with blood samples. I’ve worked as a trainer for a company that sold nucleic acid and protein assays and would go into the customers’ labs to show them how to use the kits. I’ve been in labs at huge pharma companies, large and small universities, and tiny biotech startups that didn’t even have a sink (just dump the liquids in the trash can :rolleyes:).

It’s certainly possible someone didn’t clean an instrument after use or somehow used a solution containing EDTA when they thought they were using something else. I’ve seen sampling probes with residue crystallized on the tips when it came time to use them. People are people and just because a lab is highly regulated with SOP’s about instrument cleaning and shutdown doesn’t means these are always followed every time or mistakes aren’t made.

17

Not somewhere publicly accessible. I’m sure the facility that did the testing, as a result of this incident, changed their policies to make contamination of blood samples less likely to happen. They might have even investigated what happened and gave an employee notice over it, for all we know.

But that wouldn’t be posted online or to the public at all. It’s really nobody’s business but theirs.

18

Yeah, this isn’t something a testing lab would advertize–“Send your samples to us; we’ll try our best not to contaminate them”.

On the other hand, the lawyers for the Duke lacrosse players certainly did their job in examining how the players’ DNA tests were handled and reported.

19

Please pardon my delay in replying. I did not really expect someone like you to reply. Thank you very much for doing so. :slight_smile:

The FBI and FBI toxicologist Roger Martz performed three kinds of tests. (1) HPLC (high performance liquid chromatography), (2) Negative-ion mode of LCESMSMS (liquid chromatography with tandem mass spectrometry and electrospray interface), and (3) Positive-ion mode of LCESMSMS

I believe you do not need what follows to answer my original question. But it may be helpful, and you may find it interesting.

What follows are my excerpts from Dr. Terry Lee’s testimony during the civil trial, Jan. 16, 1997

(Note: Text and information in the brackets is mine.)

Questions are from Tom Lambert, one of the plaintiff’s attorneys in the civil trial
Answers are from Dr. Terry Lee
…
Q. How long have you been affiliated with Beckman Research Center
with the City of Hope?
A. 14 years.
Q. Can you tell the jury what your position is at the City of Hope?
A. My official title is research scientist. I do studies related to
the analysis of biomolecules by mass spectrometry.
…
Q. Are you familiar with the profession known as liquid
chromatography?
A. Yes, I am.
Q. One of the processes that is at issue in this case is a cell
called HPLC test [high performance liquid
chromatography]. Are you familiar with that test?
A. Yes.
Q. How long have you been involved in doing HPLC tests?
A. Since my graduate work, so it would be in excess of 20 years.
Q. How many times have you yourself run tests using the HPLC method?
A. Hundreds of times.
Q. One of the other tests at issue in this case involves the use of
liquid chromatography combined with tandem mass spectrometry using
an electrospray interface, what Dr. Rieders referred to as LCESMSMS;
are you familiar with that technology?
A. Yes, I am.
Q. How many times have you, yourself, run tests using such
technology?
A. Hundreds of times.
…
Q. Finally, Dr. Lee, Agent Martz also performed a so-called positive
ion mode test. What kind of test is that, sir?
A. That’s a test exactly like the negative ion test except you’re
looking at the positive ions instead of the negative ions.
Q. That’s another form of the LCESMSMS testing technology?
A. That’s correct.
Q. Have you yourself performed such tests?
A. Yes.
Q. How many times?
A. Hundreds of times.
…
Q. Now, incidentally, Dr. Lee, are you familiar with the equipment
that Agent Martz used to perform these tests?
A. Yes. We have the same equipment in our laboratory.
Q. You have the very same equipment you used in your lab?
A. It’s the same mass spectrometry and the same electrospray source,
yes.
Q. Have you yourself used that equipment?
A. Yes.
Q. So you’re familiar with the equipment?A. I’m very familiar with it.
…
[Dr. Lee explains that while using the positive ion mode–a form of LCESMSMS testing–Roger Martz detected a large amount of EDTA in a purple-topped test tube stored blood, but he detected only a trace amount of EDTA in the two evidence samples.]
…
Q. As a scientist, Dr. Lee, what is the most likely explanation for
this very small trace [of EDTA] that is shown in the evidence sample here in
this one test that Agent Martz did?
A. These results are consistent with a carryover from – in the
instruments. In other words, if you first analyze on the instrument
samples which contain a large quantity of EDTA and then you
subsequently come in with the samples that don’t have any, it’s not
uncommon to pick up trace levels from various parts of the
instruments that have been contaminated with the EDTA and then
subsequently alluded off when you did the other analyses.
Q. And is that a common problem with the LCESMSMS instruments?
A. It’s a common problem with those instruments, yes.
Q. Is it something that you yourself have experienced?
A. Many times.
…
[Dr. Lee also testified that Roger Martz tested a sample of his own blood and that he detected a trace amount of EDTA equivalent to what he detected with the two evidence samples. He also explained why the defense’s expert witness, Dr. Rieders, was mistaken in his theory that the small amount of EDTA was a result of EDTA molecular degradation. As follows:]

Q. Dr. Rieders also tried to explain the difference between the
small signal from the evidence sample and the large signal from the
known sample by saying that it was possible that the EDTA in the
evidence sample had somehow degraded before these tests were run.
…
A. I believe he’s incorrect.
Q. Why is that, sir?
A. EDTA is a very stable compound; it’s not likely to degrade
under normal circumstances. And these evidence samples were – came
from different places and were treated differently; yet they all
show the same levels. And so it’s difficult to imagine the
degradation that would be common to all the samples.

[Note: Despite Dr. Lee’s expert testimony, I have read that EDTA is indeed degraded by light. Yet his argument that the two evidence samples would not show equivalently small amounts of EDTA is still valid. Specifically, the blood on the gate was exposed to open air and daylight for a number of days before it was tested. The blood from the socks was not. :cool: ]

20

So you don’t believe Dr. Lee’s testimony that it was instrument contamination? What is your theory?