Dr. John Gerdes was a clinical laboratory director who testified as a defense DNA expert about the reliability of the LAPD crime laboratory's DNA work. During four days of direct, cross, redirect, and recross examination in August 1995, he contrasted legally mandated clinical-laboratory standards with the lower, voluntary accreditation standards applicable to forensic laboratories and described persistent contamination problems and practices he said created substantial cross-contamination risks at the LAPD laboratory. On cross-examination, he acknowledged reported DNA matches and said he had no direct evidence that Simpson's reference sample had contaminated stains from the Bronco; in a later civil closing argument, plaintiffs' counsel characterized his testimony as accepting reliable RFLP results and finding no actual contamination.