📄 Gerdes LAPD Lab Contamination Study Report
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Gerdes LAPD Lab Contamination Study Report

Dr. John Gerdes' study and formal report on contamination at the LAPD crime laboratory, based on LAPD's own data. The report was still in progress during early pretrial motions and was eventually received by the prosecution as a four-page formal expert report.

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Criminal trial (3)

More in Lab Proficiency Quality Control

Cellmark 1988 CACLD Proficiency Test and Report
The 1988 California Association of Crime Laboratory Directors proficiency test administered to Cellmark (49 samples, 1 false positive attributed to inadvertent cross-contamination that Cellmark did not detect itself). Defense 1154 is the six-page CACLD repor…
Gerdes Chart — LAPD Run Contamination by Month
Chart showing the percentage of LAPD PCR runs with contamination by month from May 1993 through August 1994, used by Gerdes to document contamination patterns in the LAPD laboratory; Defense 1295.
Gerdes Chart — LAPD Runs and Strips May–July 1994
Chart showing the percentage of LAPD PCR runs and strips with contamination and/or artifacts from May through July 1994, with monthly bars approximating 33%, 31%, and 17%; Defense 1297.
LAPD PCR Validation Training Record
LAPD PCR method validation training record stating that every validation sample either gave the expected typing result or no typing result, introduced as Defense 1181-A. Gerdes contradicted this claim by pointing to Yamauchi's actual hybridization records.
CACLD Blind Trial Proficiency Report (Defense 1183)
Nine-page California Association of Crime Laboratory Directors report on blind proficiency trial results, introduced and cross-referenced during testimony about LAPD and Cellmark testing practices.
Four Types of Proficiency Tests Diagram
Hand-drawn diagram created during Dr. Cotton's testimony categorizing proficiency tests into four types (open/blind, internal/external), introduced as Defense 1153.
Gerdes Chart — LAPD Strip Contamination by Month
Chart summarizing the percentage of LAPD PCR strips showing contamination and/or artifacts by month from May 1993 through August 1994; Defense 1287.
Gerdes Chart — LAPD Contamination by Control Type
Chart showing the percentage of contamination by extraction control type at the LAPD lab from May through July 1994, showing 10 of 25 extraction controls contaminated; Defense 1298.
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