This high-stakes day featured intensive cross-examination and redirect of LAPD criminalist Gregory Matheson, with the defense systematically building allegations that O.J. Simpson's reference blood sample was used to plant evidence at the crime scene. Blasier argued that approximately 1.5 milliliters of Simpson's blood were unaccounted for and used a hypothetical involving overnight storage in a trash bag to challenge procedures. A pivotal moment came when type B blood found under Nicole Brown Simpson's fingernails—which the defense argued does not match Simpson—was presented as evidence of an unidentified third party; the prosecution responded that the B-like result likely reflected degradation of Nicole Brown Simpson's BA blood. The prosecution countered with detailed testimony on lab security protocols, card access logs, and scientific explanations for blood degradation patterns.

• The defense poses a hypothetical calculation yielding about 1.5 milliliters under assumed starting volume and withdrawals; the original quantities and transfer losses are approximate, rather than an established missing amount.
• Defense uses a hypothetical in which a reference sample was left in a trash bag overnight to challenge evidence-handling procedures
• Defense argues the B-like fingernail results do not match Simpson and suggest unidentified third-party blood; prosecution argues the pattern likely reflects degradation of Nicole Brown Simpson's BA blood
• Prosecution presents lab card access logs and security testimony showing no unauthorized access to evidence processing room
• Heated scientific debate over EAP blood type degradation patterns; Matheson concedes observed banding pattern does not match published literature
• Defense argues for admission of knife exhibit 118, claiming its blood matched the EAP type B fingernail result; prosecution calls it a 'ludicrous' red herring