Prosecution forensic evidence dominated Day 6, with serologist Greg Matheson presenting blood typing analysis that matched O.J. Simpson's rare PGM blood subtype while excluding both victims from a crime scene drop, appearing to exclude 99.57 percent of the population. However, defense attorney Gerald Uelmen mounted an aggressive challenge to Matheson's statistical methodology, exposing racial bias in his reference population and introducing a mixture-blood scenario that could implicate tens of thousands of people. Medical Examiner Dr. Irwin Golden then testified to the fatal wounds inflicted on both victims, establishing cause of death with detailed clinical descriptions but declining to definitively identify a folding knife as the murder weapon.

• LAPD serologist Greg Matheson testified that crime scene blood drop item 49 matched O.J. Simpson's blood profile, statistically excluding 99.57 percent of the population
• Defense exposed racial bias in Matheson's reference population data, undermining the reliability of his frequency calculations
• Matheson conceded that if the blood drop was a mixture from two people, approximately 40,000-80,000 people in Los Angeles could potentially match
• Medical Examiner Dr. Irwin Golden detailed the fatal neck wound on Nicole Brown Simpson—a single cutting wound severing both carotid arteries and jugular veins
• Dr. Golden testified about all sharp force wounds on both victims but declined to definitively identify a folding knife shown to him as the murder weapon