Barry Scheck dominated the day with a devastating cross-examination of LAPD DNA analyst Collin Yamauchi, systematically attacking the lab's validation procedures, evidence handling protocols, and documentation standards. Key admissions emerged: the reference blood sample was extracted in the same session as evidentiary samples, the blood vial arrived unsealed contrary to protocol, and Yamauchi observed no blood on the socks during an initial June 29th examination—supporting the defense's planting theory. Yamauchi's credibility was further undermined by inconsistencies between his vague August 1994 statements and newly precise trial recollections, while gaps in lab notes exposed the absence of timestamps and clear procedural tracking.

• Barry Scheck forces Yamauchi to admit a typing discrepancy in validation study (1.2,4 vs. expected 1.2,1.3) that was never flagged in any written report
• Yamauchi concedes reference blood extracted in same session, location, and timeframe as Bundy evidentiary samples—suggesting potential cross-contamination
• Defense reveals O.J. Simpson's blood vial arrived at lab unsealed, contradicting LAPD protocol
• Yamauchi admits he observed no blood on socks during June 29th evidence review—bolstering defense planting theory
• Yamauchi's memory exposed as inconsistent: vague in August 1994 but newly specific with details emerging for first time during cross-examination
• Judge Ito sustains objection to improper question about Simpson's 'airtight alibi' and instructs jury to disregard
• Prosecutor Harmon demands immediate discovery and threatens sanctions for bad faith non-production