In June 1985, a serial killer began phoning the family of one of his victims. Using the recorded phone calls, John Douglas reveals what drove Larry Gene Bell to taunt this family and how he helped ensure Bell was convicted for his crimes.

Gary Heidnik lured several African American women into his Philadelphia basement where he held them prisoner, tortured them in a pit, and murdered two of them. John Douglas reveals secret clues inside the man's twisted past.

John Wayne Gacy lived a life of duplicity as a respected civic leader while also killing at least 33 men and hiding them in his crawl space. John Douglas uses never before seen FBI interview tapes to decode how and why Gacy got away with it for so long.

David Berkowitz, known as the Son of Sam, terrorized NY in the 1970s. He brought the city to its knees, killing seven and wounding six, all as rumors of ties to a satanic cult emerged. John Douglas sat down with Berkowitz to separate fact from fiction.