Park Elliott Dietz

Forensic psychiatrist Dr. Park Dietz has served as an expert witness for the prosecution in the murder trials of John Hinkley, Joel Rifkin, Jeffrey Dahmer and others. In each case he presented evidence against the defense of insanity, saying that these men knew that they were committing terrible crimes. Dietz also has a consulting firm, Threat Assessment, which focuses on workplace violence. He is a consultant to the HBO special "Murder 9 to 5," which examines murder at work.