Peter Neufeld served as a defense attorney and DNA specialist, appearing on 56 trial days and working with Barry Scheck and Robert Blasier in proceedings concerning forensic and DNA evidence. He cross-examined LAPD criminalist Andrea Mazzola about evidence-collection practices, documentation, prior testimony, and videotaped collection activity. Neufeld also cross-examined prosecution DNA experts Dr. Bruce Weir and Dr. Robin Cotton about population-frequency calculations, laboratory controls, evidence handling, and procedures; Weir acknowledged errors and presented corrected calculations with varying effects, while Cotton addressed missing substrate controls and reagent blanks.