Renee Montgomery was a criminalist at the California Department of Justice's Berkeley DNA laboratory who testified about D1S80 blood typing results from crime scene evidence. Prosecutor Rockne Harmon walked her through her scientific background — a UC Davis degree in environmental toxicology followed by post-graduate genetics coursework — but defense attorney Robert Blasier's aggressive cross-examination exposed gaps: Montgomery had never performed D1S80 testing before developing the program specifically for this case, and the system lacked proper validation and prior casework experience. She returned months later during the civil trial alongside fellow DNA experts Robin Cotton and Gary Sims, where the defense again attacked the reliability of the testing methods, citing documented lab error rates.