Marcia Clark served as lead prosecutor for the People, appearing across both the preliminary hearing and criminal trial over 156 days — one of the most sustained presences in the courtroom. She personally examined dozens of witnesses spanning the full arc of the case, from limousine driver Allan Park and houseguest Kato Kaelin to key detectives like Mark Fuhrman, Philip Vannatter, and Tom Lange, as well as forensic experts including criminalist Gregory Matheson and DNA analyst Michele Kestler. Clark delivered the prosecution's opening statement alongside Christopher Darden, methodically laying out the timeline, forensic evidence, and blood trail linking Simpson to both crime scenes, and she proved an aggressive cross-examiner — challenging defense timeline witnesses on credibility and coordination, and challenging defense toxicologist Dr. Fredric Rieders's testimony through sustained attacks on his conclusions. Her own undocumented visit to the Bundy crime scene became a point of scrutiny during the trial, forcing her to provide an account as an officer of the court.