Defense attorney Peter Neufeld spent the day cross-examining LAPD SID criminalist Andrea Mazzola about her experience, training, adherence to collection protocols, documentation, and differing accounts of who collected blood drops at Rockingham. The prosecution-produced demonstration video showed her hand contacting dirty concrete before she handled tools and material, swatches falling, and no glove change between items 5 and 6, supporting a conditional contamination possibility rather than establishing actual transfer to a swatch. The examination raised questions about the handling and documentation of blood evidence, including Mazzola's post-testimony reconstruction meeting with Dennis Fung and subsequent field-note entries.

• Mazzola admitted she was a probationer with only 2 prior crime scenes yet served as the primary blood stain collector in the Simpson case
• Mazzola testified that no manual or textbook was given to her or available for reference at the scene, and that she had received no instruction on assessing whether a crime scene had been altered
• Mazzola gave three contradictory versions of who collected blood drops at Rockingham with no notes or documents to explain the shifts
• Post-testimony meeting between Mazzola and supervisor Fung to reconstruct evidence collection, followed by new entries in field notes
• The prosecution-produced demonstration video showed Mazzola resting her right hand on dirty concrete, later handling tweezers and a chem-wipe with that hand, dropping swatches, and not changing gloves between items 5 and 6
• The prosecution still-photo demonstration board did not show the dropped swatches and appeared to omit envelope documentation
• Mazzola testified that she had no present recollection of red stains on the Bronco driver's-side door sill and that no phenolphthalein test of the sill was recorded in her notes