Peter Neufeld conducted an extensive cross-examination of DNA expert Dr. Robin Cotton throughout the day, systematically attacking the prosecution's DNA evidence through failures in lab procedures and chain of custody. The defense established critical vulnerabilities: LAPD never sent required substrate controls to Cellmark, Cellmark failed to run reagent blank controls on key evidence items, and the lab had never conducted blind external proficiency testing. Most damaging, Neufeld drew stark parallels between Cellmark's documented false positives from 1989 and the DNA quantity found in disputed evidence item 52. The prosecution's redirect examination could only partially repair ground, leaving the jury with serious questions about the DNA evidence's reliability.

• Peter Neufeld's extended cross-examination of Dr. Robin Cotton consumed the entire court day
• Defense proved LAPD never sent required substrate control swatches to Cellmark for items 47, 48, 50, 52
• Cellmark admitted failing to run reagent blank controls during extraction of items 49 and 50, violating its own protocol
• Cellmark conceded it conducted zero blind external proficiency tests in its entire six-year operating history
• Neufeld exposed Cellmark's two false positive DNA matches from 1988-1989 CACLD proficiency testing
• Defense established that item 52's DNA quantity (25-50 nanograms) fell within the same range as the contaminant in the 1989 false positive
• Only two people in Cellmark's entire African-American database matched Simpson's full DNA profile across all five loci