Defense attorney Peter Neufeld conducted a devastating cross-examination of LAPD criminalist Andrea Mazzola, systematically exposing inconsistencies in her evidence collection procedures, field notes, and testimony. Key attacks included catching her changing testimony about the Bundy gate and gloves after a lunch recess, video evidence showing her posse box locked 11 minutes after her recorded collection times, and contradictions about handling Simpson's blood vial. Judge Ito ordered LAPD to produce original evidence items for cross-examination and instructed the jury to disregard inadmissible phenolphtalein test results. By day's end, Mazzola's credibility as the prosecution's central evidence collector had been substantially damaged.

• Neufeld caught Mazzola changing testimony about the Bundy gate and whether the hat and glove were touching after prosecutors showed her photographs during lunch recess
• Video evidence (People's 186) showed Mazzola and Fung locked their posse box 11 minutes after the 1700 hours collection time she had recorded
• Missing second lens discovered in eyeglasses evidence envelope with no explanation for its disappearance
• Mazzola admitted testimony changed about whether she remained at Fung's side versus sitting on a couch with eyes closed, with no explanation for the shift
• Jury instructed to disregard positive phenolphtalein test results due to lack of confirmatory testing
• Judge Ito threatened to suppress evidence entirely if LAPD did not produce original coin envelopes and bindles for cross-examination
• Mazzola's November 1994 meeting with Kestler and DA investigators revealed to have been secretly recorded, undisclosed to defense