Robert Ressler is considered the world's leading authority on violence in contemporary society. Founder and former director of the FBI's acclaimed Violent Criminal Apprehension Program, Ressler is an expert on serial killers (a phrase he coined) and sexual homicides. He is the acknowledged true-life hero of the movie Silence of the Lambs and has consulted to the movie Copycat. The hit television series The X Files was inspired by Ressler's work at the FBI's Behavioural Science Unit.

He has investigated and interviewed the most notorious serial killers of recent years, including Jeffrey Dahmer, John Wayne Gacy, Charles Manson, Ted Bundy, and David Berkowitz. For most of his twenty-year career at the FBI, Ressler was the heart of the effort that has made the Bureau legendary; identifying and capturing violent criminals.

Author of the international best seller Whoever Fights Monsters and Justice is Served, as well as, his most recent book, I Have Lived in the Monster, Ressler received the American Academy of Psychiatry and Law's Amicus Award for contributions to the field and has been honored by the American Academy of Forensic Science. He is frequently called to assist international investigations as far away as Russia, South Africa, Japan, and Malaysia and serves as a consultant to Scotland Yard.