Day 64 was dominated by the prosecution's direct examination of LAPD chemist Gregory Matheson, who testified extensively about forensic evidence collection procedures, contamination science, and chain of custody protocols. The prosecution methodically established that improper collection techniques cannot alter blood type markers—a direct rebuttal to defense contamination arguments. Pre-trial motions centered on exhibit admissibility and evidentiary disputes, while one juror was replaced mid-day.

• Juror #2 excused for good cause; alternate #1427 selected as replacement.
• Prosecution began extensive direct examination of Gregory Matheson, LAPD Chief Forensic Chemist, establishing credentials and expertise.
• Matheson testified about SID facility security, evidence collection procedures, and his own collection of blood from the Bronco console.
• Pre-trial dispute over admissibility of 'inconclusive' blood-typing results from fingernails; court ruled issue goes to weight, not admissibility.
• Prosecution used hypotheticals to establish that improper collection adds material but does not change genetic markers.
• Defense testing of evidence samples became contentious during post-lunch motions.
• Jury excused early (4:25 PM) due to exhibit dispute regarding People's 209 evidence disposition chart.