Redirect examination of Greg Matheson (2 of 2)

📄 Redirect examination of Greg Matheson (2 of 2) — Friday, July 8, 1994

Address:

C:\DEPT103\PRELIMINARY\1994\JUL\8\REDIRECT-EXAMINATION-OF-GREG-M.DOC

TRIAL

▲ Day 6 of 6

◀ Redirect examination of Greg Matheson Recross-examination of Greg Matheson ▶

Witness: Gregory Matheson
Examiner: Marcia Clark
Called by: Prosecution • Date: Friday, July 8, 1994 • Utterances: 23

Marcia Clark redirects Greg Matheson on item 49, a blood stain with a 2+2- PGM subtype. Clark establishes that if the stain were a mixture from two people, both would need to share that rare PGM subtype — which neither victim has — and that no test exists to definitively rule out or confirm a two-person mixture. The testimony reinforces that the stain's profile is consistent with a single contributor.

# 1 THE COURT:

Miss Clark.

# 2 MS. CLARK:

Yes.

# 3

REDIRECT EXAMINATION

# 4

BY ms. clark:

# 5 Q:

Mr. Matheson, is there anything in the stain marked item 49 that indicates to you it is, indeed, a mixture of blood from two people?

# 6 A:

Well, I would not necessarily know that. Like I mentioned earlier, the results would be the same; but there is nothing specific to indicate it is a mixture or it is not a mixture.

# 7 Q:

If indeed item No. 49 came from two individuals, then they would both have to have a pgm subtype of 2+2- somewhere in there?

# 8 A:

You would have to have at least one of the factors. If it is approximately an equal mix, like I mentioned earlier, in the example, if it was a different subtype, I would expect to see that other type show up. So if we did, in fact, have a mixture, the additional blood would have to be either a 2+2- or a 2+ or a 2-.

# 9 Q:

And, in fact, at least neither of the two victims have that?

# 10 A:

That's correct.

# 11 Q:

And then that other person would also have to be a type 1 for esd?

# 12 A:

That's correct.

# 13 Q:

And an o or an a as to the abo system?

# 14 A:

Yes, that's correct.

KEY QUOTE

# 15 Q:

Are you familiar with the term known as "titering"?

# 16 A:

Yes.

# 17 Q:

Would you be able to, in fact, titer the stain known as item No. 49 with respect to esd or pgm subtype to determine the quantities with respect to being able to either rule out or limit the possibility of it being the blood of two different people?

# 18 A:

I don't believe that would be appropriate testing to determine something like that. I am not sure you could determine something like that.

KEY QUOTE

# 19 Q:

Is there any test you are aware of that could eliminate completely the possibility of that being two people?

# 20 A:

Not to my knowledge, no.

KEY QUOTE

# 21 Q:

But there was no independent evidence that you were able to find that determined that, in fact, that was indeed the blood of two people?

# 22 A:

That's correct.

# 23 MS. CLARK:

Thank you.

Temperature

procedural

Key Quotes (3)

Witness

Not to my knowledge, no.

Matheson concedes no test can completely eliminate the possibility of a two-person mixture, but Clark has already established this is an academic concern given the victims' profiles.

Witness

That's correct.

Confirms that neither victim has the 2+2- PGM subtype, meaning neither victim's blood could account for a second contributor to item 49.

Witness

I don't believe that would be appropriate testing to determine something like that. I am not sure you could determine something like that.

Closes off the defense's implied avenue — that titering could quantify contributors — by noting the test wouldn't be appropriate or definitive.

Evidence (1)

Informal

Item 49 — blood stain with PGM subtype 2+2-, discussed for whether it could be a mixture of two people's blood

discussed

Notable Exchanges (1)

Marcia Clark•Greg Matheson

Clark methodically closes off the defense's mixture theory by walking through the statistical improbability: any second contributor to item 49 would need to match on PGM subtype, ESD type 1, and ABO group O or A — and neither victim fits.

strategic

Objections

None recorded

Proceeding 8989 • 23 utterances • Prosecution witness

Preliminary Trial

Department 103