Barry Scheck served as the defense team's DNA and forensic evidence specialist, spearheading the strategy to challenge the prosecution's physical evidence through meticulous attacks on collection procedures, chain of custody, and laboratory protocols. His cross-examination of LAPD criminalist Dennis Fung stretched across multiple days, using crime scene videotape to expose contradictions in Fung's testimony, revealing that lab procedures relied on "oral tradition" rather than written protocols, and forcing admissions about critical gaps including mishandled blood swatches and missing reference blood. Beyond Fung, Scheck examined key forensic witnesses on both sides, from DNA analysts Collin Yamauchi and Gary Sims to defense expert Dr. John Gerdes, building a sustained case that the physical evidence was too compromised to trust.