Park Dietz, MD, PhD, MPH (born 1948), is a forensic psychiatrist who has consulted or testified in many of the highest profile US criminal cases including Jeffrey Dahmer, The Unabomber, the Beltway sniper attacks, and Jared Lee Loughner. He came to national prominence in 1982 during his five days of testimony as the prosecution’s expert witness in the trial of John Hinckley, Jr., for his attempted assassination of President Reagan on March 30, 1981. Then an assistant professor of psychiatry at Harvard Medical School, Dietz testified that at the time of the shooting, Hinckley knew what he was doing, knew it was wrong, and had the capacity to control his behavior thus was not legally insane.
Dietz is also a criminologist, and in 1987 he created the specialty of workplace violence prevention in founding Threat Assessment Group, Inc. (TAG), which specializes in analyzing and managing threatening behavior and communications, stalking, risks arising from domestic violence, and other abnormal activity in corporations, colleges, and schools. As of 2013, more than 20,000 senior corporate managers have attended TAG training seminars.
A separate company, Park Dietz & Associates (PD&A), is a forensic consulting firm specializing in criminal behavior analysis, forensic psychiatry, forensic psychology and other forensic sciences, serving prosecutors, criminal defense attorneys, and attorneys representing defendants and plaintiffs in civil litigation. PD&A’s national roster of experts includes physicians, psychologists, and retired FBI agents with wide expertise on the forensic aspects of fields as diverse as neurology, social work and pathology. Both TAG and PD&A are headquartered in Southern California with PD&A having a second office in Washington, D.C.
The Los Angeles Times called Dietz, “America’s best-known forensic psychiatrist.” On the TV crime drama Law and Order: Criminal Intent, the detective Robert Goren (played by Vincent D’Onofrio) is based on Dietz, who also served as a forensic consultant to that show and the original Law & Order series. A 2006 profile of Dietz in the British national newspaper The Independent quoted him as saying that both he and the Goren character possess, “idiot savant knowledge of obscure things that pop up in relation to crimes.”