📄 Cross-examination of Dr. John Gerdes (afternoon, part 3) — Thursday, August 3, 1995
Address:
C:\DEPT103\CRIMINAL\1995\AUG\3\CROSS-EXAMINATION-OF-DR-JOHN-G.DOC
TRIAL
▲ Day 128 of 167

Cross-examination of Dr. John Gerdes (afternoon, part 3)

Witness: Dr. John Gerdes
Examiner: George Clarke
Called by: Defense • Date: Thursday, August 3, 1995 • Utterances: 195
George Clarke cross-examines DNA expert Dr. John Gerdes on the fourth and fifth of five errors he identified in LAPD's DNA validation studies. Clarke methodically challenges whether the alleged errors are actually errors at all, forcing Gerdes to concede on several points — including that the analysts called the types correctly — while Gerdes maintains that contamination explains the anomalous results.
1 (Peo's 562 for id = record)
2 MR. CLARKE:

Dr. Gerdes, referring you to what will be exhibit 562, is that a similar record?

3 DR. GERDES:

Yes, it is.

4 MR. CLARKE:

And you have--

5 DR. GERDES:

I'm looking.

6 MR. CLARKE:

--a copy?

7 (Brief pause.)
8 DR. GERDES:

Yes, I do.

9 MR. CLARKE:

All right. Your Honor, if I may display 562?

10 THE COURT:

Yes.

11 MR. CLARKE:

Your Honor, for the hybridization number in the upper right-hand corner is 37. I don't know if the Court wants me to go back and describe the--

12 THE COURT:

No.

13 MR. CLARKE:

All right.

14 MR. CLARKE:

Dr. Gerdes, referring you to 562, this is a hybridization run conducted also in September of `93?

15 DR. GERDES:

Yes, September 21st.

16 MR. CLARKE:

And in fact this is just what, four hybridization records later than the previous one?

17 DR. GERDES:

Yes.

18 MR. CLARKE:

So part of the same validation studies by the LAPD?

19 DR. GERDES:

Yes.

20 MR. CLARKE:

And in particular, with regard to this sample, this is a--the fourth of five errors that you have testified to previously?

21 DR. GERDES:

Correct.

22 MR. CLARKE:

In particular, the analyst was Erin Riley?

23 DR. GERDES:

Yes.

24 MR. CLARKE:

And the confirming analyst was Collin Yamauchi?

25 DR. GERDES:

Yes.

26 MR. CLARKE:

So their roles have basically reversed?

27 DR. GERDES:

Yes.

28 MR. CLARKE:

With regard to this sample, you identified an error with regard to which individual strip or sample?

29 DR. GERDES:

Item 21-1 which is no. 3.

30 MR. CLARKE:

So the third column--I'm sorry, third row down?

31 DR. GERDES:

Third row down.

32 MR. CLARKE:

That is labeled under "Description"--it looks like "Mock vag swab no. 1"?

33 DR. GERDES:

Correct.

34 MR. CLARKE:

And then "SP" in parenthesis for "Sperm"?

35 DR. GERDES:

Yes.

36 MR. CLARKE:

And then the sample below that, would that then be also the e-cell or victim's cell portion of the same vaginal swab?

37 DR. GERDES:

It is.

38 MR. CLARKE:

Now, off to the right of item no. 3, that is the third item down, the results are written in "1.2, 4," correct?

39 DR. GERDES:

Correct.

40 MR. CLARKE:

Incidentally, is this the same sample that was run previously in what you have described as error no. 3?

41 DR. GERDES:

It is the same sexual assault standard, yes.

42 MR. CLARKE:

And without belaboring the point, you don't disagree with the particular types noted by the analysts, do you?

43 DR. GERDES:

No, I don't.

44 MR. CLARKE:

In fact, you agree with them?

45 DR. GERDES:

I do.

46 MR. CLARKE:

That they were called appropriately in terms of the types present?

47 DR. GERDES:

Correct.

48 MR. CLARKE:

And your opinion about this particular error, would it be based on the exact same reasons that you gave with respect to the previous hybridization record?

49 DR. GERDES:

That's correct.

50 MR. CLARKE:

And in your view this then constitutes the fourth of five errors?

51 DR. GERDES:

That's correct.

52 MR. CLARKE:

And again just to be clear, this particular result of 1.2, 4 again is consistent with the victim in both portions?

53 DR. GERDES:

That's correct.

54 MR. CLARKE:

And in fact would your answers be the same, that such an occurrence is not unexpected with a sexual assault sample in actual casework?

55 DR. GERDES:

That the victim's DNA would be found in that fraction, that is not uncommon.

56 MR. CLARKE:

And in fact that an experienced analyst would not be surprised by that?

57 DR. GERDES:

Correct.

58 (Discussion held off the record between the Deputy District Attorneys.)
59 MR. CLARKE:

Dr. Gerdes, with respect to both this run and the previous error that you have described, you are not offering the opinion that these were called wrong by the analysts, are you?

60 DR. GERDES:

No, I'm not.

61 MR. CLARKE:

You are just--you are offering the opinion that errors were committed because the analyst didn't detect what you feel should have been detected?

62 DR. GERDES:

That's correct.

63 MR. CLARKE:

Have you reviewed any notes about what was observed in terms of any steps prior to typing these samples?

64 DR. GERDES:

I've read testimony or heard testimony, read testimony, I believe, that these were observed microscopically to confirm sperm was there.

65 MR. CLARKE:

And with respect to the confirmation of sperm, does an experienced analyst always obtain a result for those sperm just because they are observed?

66 DR. GERDES:

They should.

67 MR. CLARKE:

Is it your testimony that because sperm are observed there should be a PCR DQ-Alpha result for that sperm?

68 DR. GERDES:

They should--they should obtain--they should find that DNA.

69 MR. CLARKE:

Isn't it correct that there are levels of sperm that may not be detected by the DQ-Alpha system when using the appropriate number of cycles?

70 DR. GERDES:

There are levels below that, but if they observed sperm, they should not be at that level.

71 MR. CLARKE:

If there is observed sperm can't there be a low number of sperm not detectable?

72 DR. GERDES:

If they observe sperm there is an adequate amount.

73 MR. CLARKE:

Is it your testimony that if there is sperm seen there should be a result up there?

74 DR. GERDES:

Yes.

75 MR. CLARKE:

And it is based on that testimony that you offer the opinion this was a fourth error?

76 DR. GERDES:

Based on that, and also if you look at the time frame around this period, there is a 4 allele that is circulating through the lab which in my opinion--

77 MR. CLARKE:

Objection, nonresponsive, move to strike.

78 THE COURT:

Sustained.

79 MR. CLARKE:

All right. Your Honor, I would ask to have one final photograph marked, if I may.

80 THE COURT:

Yes.

81 MR. CLARKE:

Would that be 563?

82 THE COURT:

Yes.

83 (Peo's 563 for id = photograph)
84 MR. CLARKE:

Showing you, Dr. Gerdes, another similar photo, does that appear familiar?

85 DR. GERDES:

Yes.

86 MR. CLARKE:

And is that labeled "Hybridization 199"?

87 DR. GERDES:

That's correct.

88 MR. CLARKE:

And you have a copy of that?

89 DR. GERDES:

I do.

90 MR. CLARKE:

Your Honor, may I display this?

91 MR. CLARKE:

Dr. Gerdes, does this strip reflect the final error that you described in your testimony yesterday?

92 DR. GERDES:

Yes.

93 MR. CLARKE:

First of all, in terms of the date, the date is May 25th, `94?

94 DR. GERDES:

Correct.

95 MR. CLARKE:

The analyst is whom?

96 DR. GERDES:

Harry Klann.

97 MR. CLARKE:

HK?

98 DR. GERDES:

HK.

99 MR. CLARKE:

This particular run consists of what?

100 DR. GERDES:

A series of hairs that were analyzed and they are reference hairs.

101 MR. CLARKE:

Now, by reference hairs what do you mean?

102 DR. GERDES:

They are from known individuals at the laboratory, so they are just presumably cleanly picked out of the person's head and then run.

103 MR. CLARKE:

The particular error that you have identified relates to what sample?

104 DR. GERDES:

It is the fifth lane down.

105 MR. CLARKE:

Which is labeled under item number there is dash 10?

106 DR. GERDES:

Correct and then no. 27 S.

107 MR. CLARKE:

S, so this would be--well, let's just start off to the far left. It is actually no. 5 as written in the far left-hand column?

108 DR. GERDES:

Correct.

109 MR. CLARKE:

And then it is no. 5 under "Tube number"?

110 DR. GERDES:

Correct.

111 MR. CLARKE:

And then dash 10?

112 DR. GERDES:

Correct.

113 MR. CLARKE:

Under "Item number" I just want to make sure we are clear on which row.

114 DR. GERDES:

Correct.

115 MR. CLARKE:

And then it is labeled "No. 27 s"?

116 DR. GERDES:

Correct.

117 MR. CLARKE:

That is what type of sample?

118 DR. GERDES:

That is a hair shaft from one of these references.

119 MR. CLARKE:

Is it the case that that is a hair shaft from the named--or what appears to be the first name of a person immediately above that sample?

120 DR. GERDES:

That's correct.

121 MR. CLARKE:

What looks like "Jerry B."?

122 DR. GERDES:

It also says "No. 27" before that, so that is what you go by.

123 MR. CLARKE:

Okay. Now, that sample above the one that we are interested in that says "No. 27, Jerry B."--

124 DR. GERDES:

Correct.

125 MR. CLARKE:

--is that the root of that hair shaft?

126 DR. GERDES:

It is.

127 MR. CLARKE:

The sample that you have offered the opinion is an error relates to the shaft itself, correct?

128 DR. GERDES:

Correct.

129 MR. CLARKE:

As far as the root of that hair is concerned, was that correctly called?

130 DR. GERDES:

Yes.

131 MR. CLARKE:

Where is the DNA in a hair?

132 DR. GERDES:

It is found in the root.

133 MR. CLARKE:

It is found in the root only, isn't it?

134 DR. GERDES:

That's correct.

135 MR. CLARKE:

Can hair shafts be typed for DNA?

136 DR. GERDES:

Hair shafts are generally considered to be substrate controls if they are at a crime scene. That is, they should not have DNA.

137 MR. CLARKE:

In other words, if a hair were sterily removed from a person's hair and maintained in an absolute sterile condition and then typed using the system, there would be no DNA result, correct?

138 DR. GERDES:

Correct.

139 MR. CLARKE:

As far as the root, the root hair--and I'm talking about one above the sample that we are interested in.

140 DR. GERDES:

Uh-huh.

141 MR. CLARKE:

--that typed as the same type as Jerry B., correct?

142 DR. GERDES:

Correct.

143 MR. CLARKE:

Which is a 2, 3?

144 DR. GERDES:

Correct.

145 MR. CLARKE:

The hair shaft that you have offered the opinion is an error, is it correct that the 1.2 allele was noted by the analyst?

146 DR. GERDES:

Yes.

147 MR. CLARKE:

And there was no confirming analyst in this instance, at least none noted?

148 DR. GERDES:

None noted.

149 MR. CLARKE:

The 2 allele was noted on the shaft?

150 DR. GERDES:

Yes.

151 MR. CLARKE:

A weak 3 was noted on the shaft?

152 DR. GERDES:

Yes.

153 MR. CLARKE:

And is it the case that the weak 3 is noted to be approximately the same intensity as the C dot?

154 DR. GERDES:

Correct.

155 MR. CLARKE:

You have offered the opinion that that result is incorrect; is that right?

156 DR. GERDES:

That's correct.

157 MR. CLARKE:

As far as the presence of those alleles, you don't have any--you are not rendering any conclusion that the alleles aren't present, are you?

158 DR. GERDES:

No.

159 MR. CLARKE:

As far as a hair shaft, isn't it correct that hair shafts in fact can have DNA on them?

160 DR. GERDES:

If it is from a contaminant or from a crime scene. In this case it is from a contaminant and the significant part--aspect of this particular item is that the 1.2 and 2 are--the analyst is recording this according to intensity or recorded as the type with this weak 3 so that is an incorrect type.

161 MR. CLARKE:

Well, isn't it the case there shouldn't be any type on a hair shaft if it is sterily collected and sterily maintained?

162 DR. GERDES:

That is true.

163 MR. CLARKE:

Hairs are in the real world, aren't they?

164 DR. GERDES:

Yes, but generally on reference hairs--that is why you do these reference hairs; the shafts are clean.

165 MR. CLARKE:

If somebody else plucked a hair out, had trouble plucking it out or whatever, had to deal with the hair manually, if enough of that went on, couldn't you detect the DNA of the person who pulled the hair?

166 DR. GERDES:

It certainly is possible that in the manipulation of that item in the LAPD by the way they manipulated it, they introduced foreign DNA there.

167 MR. CLARKE:

The fact that a hair shaft has DNA on it, that is not an error, is it?

168 DR. GERDES:

In this particular case I've considered this an error because on reference hairs in particular occasionally you will find a small amount of DNA on the shaft. Most likely that DNA is going to be the same type as the root and the explanation for that is when you pull the hair out there may be some epithelial cells that come across from that individual that would type. But you generally do not find any DNA there, and if you do find DNA there, it should match the person that that hair came from. In this case it doesn't. There is a 1.2 that is coming from somewhere else.

169 MR. CLARKE:

Dr. Gerdes, how many cases have you consulted with a Defense attorney on that have involved hairs?

170 DR. GERDES:

Probably maybe 20, 25 percent of the cases I have done.

171 MR. CLARKE:

So about--

172 DR. GERDES:

So--

173 MR. CLARKE:

So about seven or eight?

174 DR. GERDES:

Something like that.

175 MR. CLARKE:

In those cases did all the hair shafts type with no results on them?

176 DR. GERDES:

Those were hairs that came from crime scenes and it is not unusual to find either both the root and the shaft at the same type or foreign DNA's on those.

177 MR. CLARKE:

So it is your complaint and it is your opinion that that is an error because this is a hair shaft and we know who it came from?

178 DR. GERDES:

That is not my complaint. I mean, it is an error because there is a 1.2 that doesn't make sense on a reference hair. If you look at reference hairs that are generally run in labs that use these kind of standards, if you find any DNA, it is the type of the individual. You don't find DNA from someone else there unless it is from a crime scene or it was collected somewhere, but might anticipate that to happen.

179 MR. CLARKE:

Is it your testimony, Dr. Gerdes, that an experienced DNA analyst would, if obtaining a result on a hair shaft, that that necessarily is an error if it is from a known person?

180 DR. GERDES:

This should be typing as a 2, 3. It types as a 1.2, 3.

181 MR. CLARKE:

Objection, nonresponsive.

182 THE COURT:

Overruled. Ask the question again.

183 MR. CLARKE:

Dr. Gerdes, is it your testimony that an experience forensic analyst who obtains a result such as this on a hair shaft from a known person would make a mistake in seeing that result?

184 MR. SCHECK:

The question, your Honor, calls for speculation.

185 THE COURT:

Overruled.

186 DR. GERDES:

That is my testimony based on the fact that this should be a 2, 3 hair because this is a reference sample.

187 MR. CLARKE:

Dr. Gerdes, there shouldn't be anything on it unless it was collected and kept in a sterile fashion, correct?

188 DR. GERDES:

This is--this is a typing error because of the fact that the introduction of a contaminant which creates the wrong dot intensities of the 1.2, 2.

189 MR. CLARKE:

You are calling this a typing error?

190 DR. GERDES:

Yes.

191 MR. CLARKE:

In other words, those alleles aren't there?

192 DR. GERDES:

No, they are there, but they are there because of introduced contamination.

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

The five errors that you have discussed in your testimony for the last hour perhaps, in your opinion those are all errors by the Los Angeles Police Department laboratory?

KEY QUOTE
195 DR. GERDES:

They are.

Temperature

tense

Key Quotes (4)

George Clarke
You are not offering the opinion that these were called wrong by the analysts, are you?
Clarke extracts a key concession: Gerdes is not saying the analysts misread results, only that they failed to detect something he thinks they should have detected — narrowing the scope of the 'error' significantly.
Dr. John Gerdes
No, they are there, but they are there because of introduced contamination.
Gerdes's core argument distilled — the alleles are real, but their presence proves contamination, not correct typing. Clarke uses this to highlight the circular nature of the reasoning.
Dr. John Gerdes
There is a 1.2 that is coming from somewhere else.
Gerdes identifies the specific contamination signature he's relying on — a foreign 1.2 allele on a reference hair shaft that should only show the donor's type.
George Clarke
The five errors that you have discussed in your testimony for the last hour perhaps, in your opinion those are all errors by the Los Angeles Police Department laboratory?
Clarke's closing summary question on this line of cross — framing the cumulative weight of Gerdes's testimony as institutional criticism of the LAPD lab.

Evidence (2)

People's 562
Hybridization record from September 21, 1993 — LAPD validation study run no. 37, analyst Erin Riley, confirming analyst Collin Yamauchi, involving mock vaginal swab sample
displayed, discussed as fourth of five errors
People's 563
Photograph of hybridization run no. 199, dated May 25, 1994, analyst Harry Klann, involving reference hair shaft samples
displayed, discussed as fifth and final error

Notable Exchanges (2)

George ClarkeDr. John Gerdes
Extended back-and-forth over whether DNA found on a reference hair shaft constitutes an error. Clarke presses that hair shafts can legitimately have DNA from handling; Gerdes insists the 1.2 allele is foreign contamination and the result should match the donor.
strategic
George ClarkeDr. John Gerdes
Clarke challenges Gerdes's fourth error by establishing that observed sperm does not necessarily yield a PCR result if sperm count is low. Gerdes holds his ground — if sperm are visible, there should be detectable DNA.
technical/probing

Credibility Attacks (2)

⚔ Dr. John Gerdes
Scope limitation / forced concession
Clarke repeatedly establishes that Gerdes is not saying the analysts called types incorrectly — only that they failed to detect issues he believes should have been flagged. Clarke also highlights that Gerdes has worked on only roughly seven or eight hair cases, questioning the depth of his hair-typing experience.
⚔ Dr. John Gerdes
Internal inconsistency / circular reasoning
Clarke forces Gerdes to acknowledge that hair shafts in casework routinely carry DNA, then presses him on why the same finding in a validation study constitutes an error — exposing that Gerdes's conclusion depends on his prior assumption about what the result should be.

Witness Demeanor

(Brief pause.) — while Gerdes reviews exhibit 562

Objections

3 objections (1 sustained, 2 overruled)
Proceeding 7943 • 195 utterances • Defense witness
Criminal Trial
Department 103
⚖️ Start
📂 AUG 3, 1995 📄 Cross-examination of Dr. John
AUG 3, 1995 KRT DvH TD