Direct examination of Dr. Robin Cotton (part 1)

📄 Direct examination of Dr. Robin Cotton (part 1) — Tuesday, May 9, 1995

Address:

C:\DEPT103\CRIMINAL\1995\MAY\9\DIRECT-EXAMINATION-OF-DR-ROBIN.DOC

TRIAL

▲ Day 70 of 167

Witness: Dr. Robin Cotton
Examiner: George Clarke
Called by: Prosecution • Date: Tuesday, May 9, 1995 • Utterances: 45

Clarke continues direct examination of DNA expert Dr. Robin Cotton, walking the jury through the basics of PCR-based DNA testing — specifically the difference between inclusion and exclusion results, and the genetic markers used in forensic analysis. The examination is largely foundational, establishing the science before getting to case-specific results, and ends abruptly mid-session on a microphone technical issue.

# 1 (The following proceedings were held in open Court, in the presence of the jury:)

# 2 THE COURT:

Thank you, ladies and gentlemen. Please be seated. Dr. Cotton, would you resume the witness stand, please. And why don't you pull the microphone close to you there, please. And, Mr. Clarke, you may continue with your direct examination.

# 3 MR. CLARKE:

Thank you, your Honor.

# 4 MR. CLARKE:

Dr. Cotton, you've described a little bit about the use of these tests, whether RFLP or PCR, to exclude people or include people; is that right?

# 5 DR. COTTON:

That's correct.

# 6 MR. CLARKE:

Is there any difference between those two things, excluding someone or including someone?

# 7 DR. COTTON:

Well, those are two different--entirely different things, but I don't--I'm not sure what you mean.

# 8 MR. CLARKE:

All right. Well, first of all, in excluding a person, what does that mean once you've conducted the test?

# 9 DR. COTTON:

You've saying that that person cannot be a contributor to the sample that you've tested.

# 10 MR. CLARKE:

What about the opposite? What about including someone?

# 11 DR. COTTON:

Including someone, you're saying that this person could be a contributor--contributor to the sample that you've tested.

KEY QUOTE

# 12 MR. CLARKE:

Is there--in terms of the use of these tests, are they capable and do they in fact serve both of those purposes?

# 13 DR. COTTON:

Yes, they do.

# 14 MR. CLARKE:

Now, as far as the use of PCR--and you've described the fact that there are genetic markers or various locations on this DNA molecule that you look at where people differ?

# 15 DR. COTTON:

That's right.

# 16 MR. CLARKE:

And you described a little bit about the selection process, the process whereby forensic science decides which markers to look at; is that right?

# 17 DR. COTTON:

That's right.

# 18 MR. CLARKE:

Are there specific genetic markers that you look at in your laboratory following PCR amplification?

# 19 DR. COTTON:

Of course.

# 20 MR. CLARKE:

Okay. Do they have names that describe them?

# 21 DR. COTTON:

Yes, they do.

# 22 MR. CLARKE:

Could you describe those for the jury, please?

# 23 DR. COTTON:

To tell you the truth, so I don't make a mistake, if you want me to list those markers, how about if you hand me one of my notebooks so I can read off of that.

KEY QUOTE

# 24 MR. CLARKE:

Sure. Would that assist you in describing each one exactly?

# 25 DR. COTTON:

I think it would, yes.

# 26 MR. CLARKE:

First of all--

# 27 MR. CLARKE:

I'm sorry.

# 28 THE COURT:

Go ahead.

# 29 MR. CLARKE:

First of all, Dr. Cotton, these what appear to be two binders, could you just tell us what they are?

# 30 DR. COTTON:

The two binders have copies in them of our original case folder, and I have the original case folder in my briefcase, but these are easier to manipulate.

# 31 MR. CLARKE:

In other words, those are easier for you to work with?

# 32 DR. COTTON:

That's right.

# 33 MR. CLARKE:

Actually, let me approach it slightly differently. Is there a marker that you examine using the PCR process called DQ-alpha?

# 34 DR. COTTON:

Yes.

# 35 MR. CLARKE:

What is DQ-alpha?

# 36 DR. COTTON:

DQ-alpha is located on chromosome 6 and it is one of the human leukocyte antigen markers. These microphones are doing funny things.

# 37 MR. CLARKE:

Okay.

# 38 THE COURT:

Why don't you take it off, take off the wireless, hand it to me.

# 39 (The witness complies.)

# 40 THE COURT:

Thank you.

# 41 MR. CLARKE:

Now, you used a fairly large term, human leukocyte antigen?

# 42 DR. COTTON:

That is the name, generic name of the set of genes for which DQ-alpha is one. They are surface--they code for proteins that are on the surface of cells, and DQ-alpha is one of these proteins that's been very well characterized, and the DNA that encodes this protein is also very well characterized.

# 43 MR. CLARKE:

Dr. Cotton, could you pull that microphone just a little closer to you?

# 44 THE COURT:

Did you disconnect the Court's microphone?

# 45 AUDIO PERSON:

Yes, your Honor.

Temperature

procedural

Key Quotes (3)

Dr. Robin Cotton

Including someone, you're saying that this person could be a contributor--contributor to the sample that you've tested.

Establishes the critical distinction that DNA inclusion is probabilistic, not absolute — a point the defense would later exploit.

Dr. Robin Cotton

To tell you the truth, so I don't make a mistake, if you want me to list those markers, how about if you hand me one of my notebooks so I can read off of that.

Candid moment of scientific caution — Cotton preferred accuracy over recall, projecting credibility.

Dr. Robin Cotton

These microphones are doing funny things.

Minor but humanizing aside during otherwise dry technical testimony.

Evidence (1)

Informal

Two binders containing copies of Cotton's original case folder, used as reference during testimony

introduced as working reference

Notable Exchanges (1)

Lance A. Ito•Dr. Robin Cotton

Judge intervenes to handle a malfunctioning wireless microphone, taking it from the witness and having the court's wired microphone connected instead.

routine

Light Moments (1)

Dr. Robin Cotton

Dr. Cotton interrupts her own technical testimony to note the microphones were 'doing funny things,' prompting Ito to personally take the wireless mic from her.

Witness Demeanor

(The witness complies.) — removes wireless microphone and hands it to the judge

Objections

None recorded

Proceeding 5962 • 45 utterances • Prosecution witness

Criminal Trial

Department 103