Direct examination of Dr. John Gerdes (part 9)

📄 Direct examination of Dr. John Gerdes (part 9) — Wednesday, August 2, 1995

Address:

C:\DEPT103\CRIMINAL\1995\AUG\2\DIRECT-EXAMINATION-OF-DR-JOHN-.DOC

TRIAL

▲ Day 127 of 167

◀ Sidebar: prosecution (2) Motion scheduling discussion ▶

Witness: Dr. John Gerdes
Examiner: Barry Scheck
Called by: Defense • Date: Wednesday, August 2, 1995 • Utterances: 32

Barry Scheck continues his direct examination of DNA expert Dr. John Gerdes, focusing on a photograph of the chelex extraction solution used at the LAPD lab. Gerdes notes the bottle was dated 9/12/94 and was still in use during the January 18, 1995 lab visit — implying months of reuse — contrasting this with Cellmark's practice of making fresh chelex weekly. Repeated prosecution objections on foundation and speculation grounds were partly sustained, with Judge Ito closing the session by pointedly noting the date on the bottle was 'subject to interpretation' before calling recess.

# 1 MR. SCHECK:

Well, 1306, what is this a picture of?

# 2 DR. GERDES:

This is a picture of the chelex extraction solution that is used for DNA extraction and it is located in the chemical fume hood that we saw a few moments ago.

# 3 MR. SCHECK:

Who directed you to this? Mr. Yamauchi?

# 4 DR. GERDES:

Mr. Yamauchi.

# 5 MR. SCHECK:

And could we zoom in here on the label on that bottle. Is there a date there that has some significance?

# 6 DR. GERDES:

Yes, there is.

# 7 MR. SCHECK:

What is that?

# 8 DR. GERDES:

It is 9/12/94 is the date that is on the chemical refers to the date in which it was--it was made up, and we were visiting this laboratory on January 18th. At least these pictures were taken on January 18th, 1995. That indicates that this particular chemical has been there a number of months and has been used over and over, over those months.

# 9 MR. SCHECK:

Is that a good laboratory practice?

# 10 DR. GERDES:

Especially not in PCR.

KEY QUOTE

# 11 MR. CLARKE:

Objection, lack of foundation, also speculation.

# 12 THE COURT:

Sustained. The last two answers are stricken.

# 13 MR. SCHECK:

The solution here, what is it?

# 14 DR. GERDES:

Chelex is a solution that is used in the DNA extraction procedure.

# 15 MR. SCHECK:

Are you familiar with how the chelex solution is used in the DNA extraction procedure at LAPD according to their protocol and at other forensic labs and in other clinical labs?

# 16 DR. GERDES:

Yes.

# 17 MR. CLARKE:

Objection, lack of foundation.

# 18 THE COURT:

Overruled.

# 19 DR. GERDES:

Yes, I am.

# 20 MR. SCHECK:

What does the term "Aliquot" mean?

# 21 DR. GERDES:

Aliquot means taking a large bottle like this and splitting it into very small tubes so that there is a smaller amount of material, smaller solution amount in these tubes.

# 22 MR. SCHECK:

How is the chelex dealt with at the Cellmark laboratory?

# 23 DR. GERDES:

The chelex solution at Cellmark is made up fresh weekly.

KEY QUOTE

# 24 MR. SCHECK:

And you determined that when you took a tour in connection with this case?

# 25 DR. GERDES:

Yes, I did.

# 26 MR. SCHECK:

All right. And in your judgment is it sound laboratory practice to keep the chelex solution at least indicated here to be using it from 9/12/94 through what, January 18, `95.

# 27 MR. CLARKE:

Objection, lack of foundation, calls for speculation.

# 28 THE COURT:

Sustained.

# 29 MR. SCHECK:

Well, what is the terms of DNA laboratory methods? Is there a problem with using a chelex solution from the same bottle for a substantial period of time?

# 30 MR. CLARKE:

Objection, unintelligible.

# 31 THE COURT:

I understand it, but same objection. I think there are some people in the audience who want to step out. All right. That objection is overruled,. But it does assume facts that aren't in evidence. This particular date is subject to interpretation. There are two different ways you can interpret that date, counsel. All right. Let's take our recess at this point. All right. Ladies and gentlemen, please remember all my admonitions to you. We will be in recess for fifteen minutes. All right. Dr. Gerdes, you can step down.

# 32 (Recess.)

Temperature

tense

Key Quotes (4)

Dr. John Gerdes

That indicates that this particular chemical has been there a number of months and has been used over and over, over those months.

Core of the defense argument — LAPD was reusing chemical reagents rather than preparing fresh batches, suggesting poor lab hygiene that could compromise DNA results.

Dr. John Gerdes

The chelex solution at Cellmark is made up fresh weekly.

Direct contrast with LAPD practice, implying Cellmark follows superior protocol and undermining confidence in LAPD's DNA work.

Lance A. Ito

This particular date is subject to interpretation. There are two different ways you can interpret that date, counsel.

Judge spontaneously undercuts the defense's central exhibit before calling recess — a notable pre-emptive caution suggesting the foundation for Gerdes's testimony on this point may be weaker than Scheck presented.

Dr. John Gerdes

Especially not in PCR.

Stricken answer, but it signals Gerdes's opinion that reused chelex is particularly problematic for PCR-based DNA analysis — the method used on key evidence in this case.

Evidence (1)

1306

Photograph of the chelex extraction solution bottle at LAPD lab, showing a date of 9/12/94, located in the chemical fume hood

Displayed and examined; date used to argue prolonged reuse of reagent

Notable Exchanges (2)

Lance A. Ito•Barry Scheck

After overruling Clarke's final objection, Judge Ito independently raises that the date on the bottle has 'two different ways you can interpret' it — an unsolicited caution to the defense before calling recess, suggesting the exhibit may not prove what Scheck implied.

strategic

Barry Scheck•George Clarke

Clarke repeatedly objects on lack-of-foundation grounds as Scheck tries to establish Gerdes's expertise on lab practices at LAPD specifically; Ito splits the difference, sustaining some and overruling others.

procedural

Credibility Attacks (1)

⚔ LAPD Crime Lab / Colin Yamauchi

Documentary evidence / expert criticism

Scheck uses the dated chelex bottle (9/12/94, still in use January 1995) to argue LAPD failed to follow proper reagent preparation standards — implicitly attacking the reliability of all DNA extraction performed using that solution.

Objections

4 objections (2 sustained, 2 overruled)

Proceeding 7153 • 32 utterances • Defense witness

Criminal Trial

Department 103