Peter Gelblum served as a plaintiff attorney at Mitchell, Silberberg & Knupp, representing Frederick Goldman alongside lead counsel Daniel Petrocelli in the civil wrongful death case against O.J. Simpson. He was a workhorse of the plaintiff's trial team, examining dozens of witnesses across a wide range of topics — from domestic violence experts like Dr. Donald Dutton and Dr. Park Dietz to forensic specialists, and from neighborhood witnesses to Simpson himself during depositions. His most notable courtroom moment came during a extended cross-examination of defense photo expert Robert Groden, in which he systematically exposed resume inflation, a lack of credentials, tabloid dealings, and methodological failures, ultimately demonstrating that the alleged photographic anomalies the defense relied upon appeared across multiple frames.