📄 Direct examination of Dr. Bruce Weir (part 2) — Friday, June 23, 1995
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▲ Day 102 of 167

Direct examination of Dr. Bruce Weir (part 2)

Witness: Dr. Bruce Weir
Examiner: George Clarke
Called by: Prosecution • Date: Friday, June 23, 1995 • Utterances: 165
Prosecutor George Clarke concludes his direct examination of DNA statistics expert Dr. Bruce Weir by eliciting frequency estimates for mixed DNA stains at the Bundy crime scene, on the Rockingham glove, and inside the Bronco — now including calculations assuming three and four contributors rather than the two-contributor scenarios covered the prior day. Dr. Weir closes by endorsing the accuracy of frequency results reported by both Cellmark and the California Department of Justice.
1 THE COURT:

All right. Good morning, Dr. Weir. Doctor, you are reminded, sir, you are still under oath. And Mr. Clarke, you may conclude with your direct examination.

2 MR. CLARKE:

Thank you, your Honor. Good morning again, ladies and gentlemen.

THE JURY: Good morning.

DIRECT EXAMINATION (RESUMED) BY MR. CLARKE

3 MR. CLARKE:

Dr. Weir, good morning.

4 DR. WEIR:

Good morning.

5 MR. CLARKE:

Just a few more frequencies to report. And what I would like to have you do, Dr. Weir, is return to the Bundy crime scene results, in particular item no. 78, if that would be acceptable.

6 DR. WEIR:

That will be fine.

7 (Brief pause.)
8 MR. CLARKE:

With regard to that particular item--and I believe yesterday you described approximately how often this combination of RFLP frequencies would be observed assuming that two persons contributed to a mixture with regard to that boot drop stain; is that right?

9 DR. WEIR:

That's right, yes.

10 MR. CLARKE:

Can you describe for us also the approximate frequency that those genetic types would be found if that stain consisted of three donors or three contributors?

11 DR. WEIR:

Yes, I can. The most frequent figure is it is a 1 in one million.

12 MR. NEUFELD:

I'm sorry, Dr. Weir what table are you referring to, please?

13 DR. WEIR:

This is the table on--

14 THE COURT:

Excuse me, counsel. Would you address those comments to me, please.

15 MR. NEUFELD:

I'm sorry, your Honor.

16 THE COURT:

All right. Dr. Weir?

17 DR. WEIR:

It is the table that we gave to you this morning.

18 THE COURT:

All right. Do you have that in front of you, Mr. Neufeld? Do you have that in front of you? Doctor, what page is that?

19 DR. WEIR:

It is a single-page table, your Honor.

20 MR. NEUFELD:

I have that.

21 THE COURT:

Proceed.

22 DR. WEIR:

So the low figure was 1 in a million and the high figure is 1 in 300 million.

23 MR. CLARKE:

I am writing in 1 in one million to--

24 MR. CLARKE:

I'm sorry, 1 in how much?

25 DR. WEIR:

300 million. That is the frequency of finding that mixed stain from three contributors, three unknown contributors.

26 MR. CLARKE:

On item no. 78 in particular, the RFLP results?

27 DR. WEIR:

That's right.

28 MR. CLARKE:

Now, Dr. Weir, there appears to have been added, since yesterday, on this board, and in particular next to item no. 78, a label that says "Mix."

29 DR. WEIR:

Yes. I think that is--I think that is just to emphasize that these calculations are for mixed stain where there is evidence that there was more than one contributor to that stain and this is the frequency of getting that mixture from either looks like two or three contributors.

30 MR. CLARKE:

And I believe, to your knowledge, we also see that label "Mix" to describe other mixed stains, most of which you have already testified about yesterday?

31 DR. WEIR:

That's correct, yes.

32 MR. CLARKE:

Would that be, in your view, an appropriate way to ensure that when one looks at this chart and as to any frequencies that are written to the left of the term "Mixture," that what is being described in those frequencies is approximately how often one would see these combinations of types, assuming two contributors, which is a "2" circled and then with frequencies to the right or assuming three contributors, which is denoted by a "3" with a circle and approximate frequencies to the right of that?

33 DR. WEIR:

Yes. I think that is an accurate description. I guess we could have also put a "1" colon with the single stains. Those all assume one contributor.

34 MR. CLARKE:

All right. Very well. Now, if I could turn your attention to the glove and a few more results on that, do you have that before you now?

35 DR. WEIR:

Yes, I do.

36 THE COURT:

Mr. Clarke, I'm sorry, the Bundy crime scene board was People's exhibit--

37 MR. CLARKE:

259, your Honor.

38 THE COURT:

Thank you. Just for the record.

39 MR. CLARKE:

Thank you.

40 (Brief pause.)
41 THE COURT:

All right. Dr. Weir, did you produce a new chart for this calculation?

42 DR. WEIR:

I--

43 THE COURT:

A new report?

44 DR. WEIR:

Yes, your Honor.

45 THE COURT:

Mr. Neufeld, do you have that? This is on the glove.

46 MR. NEUFELD:

Yes.

47 THE COURT:

All right. Mr. Clarke.

48 MR. CLARKE:

Thank you, your Honor.

49 THE COURT:

And the glove board is People's--

50 MR. CLARKE:

Exhibit 272-B.

51 THE COURT:

Thank you.

52 MR. CLARKE:

Dr. Weir, with regard to this particular board, and you have at this point described a number of the results already yesterday; is that right?

53 DR. WEIR:

That's right, yes.

54 MR. CLARKE:

There again appear to be, and in the instance of this board, a number of labels that say "Mix" off to the right of the "Frequency" column?

55 DR. WEIR:

Yes.

56 MR. CLARKE:

And are those used to describe the same thing as to the term "Mix" on the previous boards, that the frequencies to the left of that word are again approximations when they are assumed to be two or three contributors to each of those particular evidence items?

57 DR. WEIR:

That's right.

58 MR. CLARKE:

Now, let's start with at the very top there appears to be an item number, actually they are all item no. 9, but there is one result at the very top of the board containing what appear to be DQ-Alpha results only; is that right?

59 DR. WEIR:

Yes, that's right, uh-huh.

60 MR. CLARKE:

In other words, that was a particular stain for which there was only one genetic marker result following the use of PCR?

61 DR. WEIR:

That's right.

62 MR. CLARKE:

Did you calculate an approximate frequency of again these two-contributor possibilities versus three-contributor possibilities as you did with the other stains yesterday?

63 DR. WEIR:

Yes, I did.

64 MR. CLARKE:

And for that uppermost stain on the results board, do you have an approximate frequency, assuming that two contributors donated that set of characteristics?

65 DR. WEIR:

Yes. For two contributors the range is from 1 in 30.

66 MR. CLARKE:

1 in 30?

67 DR. WEIR:

Yes, to 1 in 190.

68 MR. CLARKE:

And did you perform a similar calculation, assuming three contributors?

69 DR. WEIR:

Yes. For three the range is from 1 in 6 to 1 in 90.

70 MR. CLARKE:

Now, with regard to the glove, can you tell us--and what I'm referring you to now are items G1, G2 and G4?

71 DR. WEIR:

Yes.

72 MR. CLARKE:

In particular the RFLP typing results, and yesterday we spoke about assuming two contributors, can you describe for us what those approximations would be, assuming three contributors?

73 DR. WEIR:

Yes, I can. So the items G1 and G2 both have the same number of bands in the RFLP profiles so for item G1 and for G2 the range is from 1 in 3000 up until 1 in 10 million.

74 MR. CLARKE:

And that would apply also to the three-contributor situation on the RFLP results on G--I'm sorry G2?

75 DR. WEIR:

That's right, the G2, the same range, 1 in 3000 to 1 in 10 million.

76 MR. CLARKE:

And then lastly, with regard to this board, did you make a similar calculation for G4, assuming again three contributors to the RFLP mixture?

77 DR. WEIR:

Yes, I did. For three contributors the range is from 1 in 20,000 to 1 in 90 million.

78 MR. CLARKE:

With regard to that range again, what is the reason that that range could be from 20,000 to 90 million?

79 DR. WEIR:

Well, it depends on the databases used. We are assuming three contributors, all of whom are unknown to us. Any of those three can be from any racial background so that we should use any of the current databases. We don't know which to use so we use them all, we use all possible combinations, and that is just the various bands have different frequencies in the different databases.

80 MR. CLARKE:

All right. Lastly, Dr. Weir, I would like to take you to one final board.

81 (Brief pause.)
82 MR. CLARKE:

Which I believe, your Honor, is People's exhibit 260. It is labeled the "Results board" and we have described it as the results board for the Bronco.

83 THE COURT:

Thank you.

84 MR. CLARKE:

Dr. Weir, turning your attention to this particular board, is this another board that you have been provided basically a smaller Xeroxed version of?

85 DR. WEIR:

Yes, it is.

86 MR. CLARKE:

And that board or that chart that you were provided contained results as are written in currently on this board, the large chart that is here in court?

87 DR. WEIR:

That's right.

88 MR. CLARKE:

Can we turn your attention then to item no. 29, the steering wheel.

89 DR. WEIR:

Certainly.

90 MR. CLARKE:

Did you make calculations in a similar manner as you've described yesterday and this morning for various different situations in which two contributors may have provided the characteristics shown in these results or three contributors?

91 DR. WEIR:

Yes, I did.

92 MR. CLARKE:

Have you also, in the instance of the results from the Bronco automobile, calculated estimates for how often the characteristics would be seen in these pieces of evidence if four contributors were involved?

93 DR. WEIR:

Yes, I have.

94 MR. CLARKE:

Specifically with regard to item no. 29, there were results obtained from that item using PCR markers alone; is that right?

95 DR. WEIR:

That's right.

96 MR. CLARKE:

In other words, no RFLP results were obtained on that particular item?

97 DR. WEIR:

That's right.

98 MR. CLARKE:

Then using these PCR markers alone, did you calculate again for two, three and four potential contributors these same estimates of frequencies?

99 DR. WEIR:

I did.

100 MR. CLARKE:

And let's start, if we could, with no. 29 and assuming two contributors, could you give us the approximate frequency that those characteristics would be found?

101 DR. WEIR:

Yes, for two the range is from 1 in 60 to 1 in 11,000.

102 MR. CLARKE:

Did you make the same types of estimates, assuming that there were three people who provided those DNA characteristics?

103 DR. WEIR:

Yes. For three the range is from 1 in 9 to 1 in 3500.

104 MR. CLARKE:

3500?

105 DR. WEIR:

3500, thank you.

106 MR. CLARKE:

And then lastly, what about assuming four contributors?

107 DR. WEIR:

Well, if we saw four we mightn't be surprised at all, the range goes from 1 in 1--

108 MR. CLARKE:

Why 1 in 1?

109 DR. WEIR:

Well, we have some fairly common bands in this profile and if we allow four people to contribute, it is going to be very likely that amongst the four we will see the mixture.

KEY QUOTE
110 MR. CLARKE:

So would the proper way of writing it be 1 in 1?

111 DR. WEIR:

Yes, I think so.

112 MR. CLARKE:

To what? What would be the other end of the range?

113 DR. WEIR:

1 in 3000.

114 MR. CLARKE:

Now, when you use the term "1 in 1," that is what you are saying, that if four people were selected at random that there would nearly be 100 percent chance that they would have this combination of markers?

115 DR. WEIR:

That's correct.

116 MR. CLARKE:

During your attention to item 31 from the center console--and again these were results generated by PCR only?

117 DR. WEIR:

That's right, yes.

118 MR. CLARKE:

--did you make these same types of calculations for the DQ-Alpha marker and the D1S80 marker?

119 DR. WEIR:

Yes, I did.

120 MR. CLARKE:

Okay. Let's start with the assumption that there are two contributors?

121 DR. WEIR:

For item 31 and two contributors the range is from 1 in 4700--4700, to 1 in him 19,000.

122 MR. CLARKE:

4700 to 19,000?

123 DR. WEIR:

Right.

124 MR. CLARKE:

What about assuming three contributors?

125 DR. WEIR:

The range is 1 in 4600 to 1 in 71,000.

126 MR. CLARKE:

4600 to 71,000?

127 DR. WEIR:

Right.

128 MR. CLARKE:

And then lastly assuming four?

129 DR. WEIR:

The range is from 1 in 1300 to 1 in 350,000.

130 MR. CLARKE:

All right. Dr. Weir, then lastly, if I can turn your attention to items 303, 304 and 305, did you again perform this similar calculation process?

131 DR. WEIR:

Yes, I did, and these items once again have the same profile as each other so the numbers are going to be the same for the whole three, so for item 303 and assuming two contributors the range is 1 in 1400 to 1 in 18,000.

132 MR. CLARKE:

And that would be the same assuming two contributors for 303, 304 and 305?

133 DR. WEIR:

That's right, yes.

134 MR. CLARKE:

Then I will write that in on the other two.

135 DR. WEIR:

Fine.

136 MR. CLARKE:

Did you also perform a calculation assuming three contributors to each of these three stains?

137 DR. WEIR:

Yes. Then there the range is 1 in 450.

138 MR. CLARKE:

And the upper range?

139 DR. WEIR:

29,000.

140 MR. CLARKE:

And lastly, assuming four contributors to each of these stains?

141 DR. WEIR:

The range is 1 in 49.

142 MR. CLARKE:

And the upper range?

143 DR. WEIR:

69,000.

144 MR. CLARKE:

And your Honor, I have placed those numbers on People's exhibit 260.

145 THE COURT:

Yes.

146 MR. CLARKE:

Thank you.

147 THE COURT:

Thank you.

148 MR. CLARKE:

Dr. Weir, you have had an opportunity to review all of the frequencies and I'm talking about now the frequencies other than those that you've described for the mixtures over the last two days?

149 DR. WEIR:

Yes, I have.

150 MR. CLARKE:

And you have had an opportunity to examine the reports of the testing laboratories wherein they describe relative frequencies for those stains that appear to be from one person; is that right?

151 DR. WEIR:

That's true.

152 MR. CLARKE:

You have also examined the results as reported on all five of the results boards, that is, DNA results board in this case; is that right?

153 DR. WEIR:

Yes, I have.

154 MR. CLARKE:

You have examined those results, as well as the databases that these laboratories utilize; is that right?

155 DR. WEIR:

Umm, yes, the FBI's. I have not examined all the data used by DOJ in their report. I have not examined the Orange County Hispanic database. When I was doing calculations I was using FBI Hispanic.

156 MR. CLARKE:

When you performed your calculations, you utilized or used the databases from the FBI that you described yesterday; is that right?

157 DR. WEIR:

That's right, yes.

158 MR. CLARKE:

And as a result of your use of those databases and the specific results in this case, you produced your own approximate frequencies, not only for the mixtures but also for the stains that appear to come from one person?

159 DR. WEIR:

Yes, I did.

160 MR. CLARKE:

Did you compare those results that you obtained with those reported by the testing laboratories in this case, Cellmark and the Department of Justice?

161 DR. WEIR:

Yes, I did.

162 MR. CLARKE:

Do you have an opinion about the accuracy and reliability about--that is, of the results produced by those two laboratories in this case?

163 DR. WEIR:

Yes. I think the results reported generated by those, they are all good estimates of the frequencies.

KEY QUOTE
164 (Discussion held off the record between the Deputy District Attorneys.)
165 MR. CLARKE:

Thank you. I have no further questions, your Honor.

Temperature

procedural

Key Quotes (3)

Dr. Bruce Weir
Well, we have some fairly common bands in this profile and if we allow four people to contribute, it is going to be very likely that amongst the four we will see the mixture.
Explains why the Bronco steering wheel stain (item 29) produces a floor frequency of '1 in 1' when four contributors are assumed — a concession that the statistical power of the evidence weakens dramatically with each additional contributor assumed.
Dr. Bruce Weir
That's correct.
Confirming Clarke's characterization that a '1 in 1' frequency means 'nearly 100 percent chance' — the most striking number in the testimony, effectively neutralizing the Bronco steering wheel stain statistically if four contributors are posited.
Dr. Bruce Weir
I think the results reported generated by those, they are all good estimates of the frequencies.
Weir's bottom-line endorsement of Cellmark and DOJ lab frequency results, providing an independent expert seal of approval for the prosecution's DNA evidence.

Evidence (3)

People's 259
Bundy crime scene DNA results board, including item no. 78 (boot drop stain)
discussed; three-contributor frequency range of 1 in 1 million to 1 in 300 million added
People's 272-B
Rockingham glove DNA results board, including items G1, G2, G4, and item 9 (DQ-Alpha only)
discussed; three-contributor RFLP frequency ranges added
People's 260
Bronco DNA results board, including items 29 (steering wheel), 31 (center console), 303, 304, and 305
discussed; two-, three-, and four-contributor PCR frequency ranges added by Clarke on the board

Notable Exchanges (2)

George ClarkeDr. Bruce Weir
Clarke walked Weir through the logical implication of a '1 in 1' frequency for the Bronco steering wheel stain under a four-contributor model, getting Weir to confirm this means nearly 100% probability — effectively showing the stain's statistical value evaporates if enough contributors are assumed.
strategic
Peter NeufeldLance A. Ito
Neufeld briefly addressed Weir directly about which table he was referencing; Judge Ito reminded him to address the court, not the witness.
procedural

Witness Demeanor

(Brief pause.) — noted twice during exhibit identification and board transitions

Objections

None recorded
Proceeding 6525 • 165 utterances • Prosecution witness
Criminal Trial
Department 103
⚖️ Start
📂 JUN 23, 1995 📄 Direct examination of Dr. Bruc
JUN 23, 1995 KRT DvH TD