There's always more Mindhunter where Mindhunter came from. John E. Douglas, the FBI agent and criminal profiler who inspired Mindhunter's Holden Ford (Jonathan Groff), has written many books about his years working for the Bureau.
We can thank Robert Ressler for the term "serial killer." Ressler coined the phrase while working as an agent at the FBI's Behavioral Science Unit. Ressler and Douglas were pioneers in behavioral science, as well as close colleagues. "We became partners, and for a long time you didn’t hear my name around the Bureau without hearing Bob’s, and vice versa," Douglas wrote of their relationship.
After working in military and civilian law enforcement, Ressler joined the FBI in 1970. Two years later, the BSU was formed and Ressler was recruited as an agent. That's where he stayed until retiring in 1990.
Naturally, Ressler came out of these meetings with some some strange stories. John Wayne Gacy, who killed 33 teenage boys and young men in Illinois, gifted Ressler a portrait of himself as a clown. The inscription read, "Dear Bob Ressler, you cannot hope to enjoy the harvest without first laboring in the fields. Best wishes and good luck. Sincerely, John Wayne Gacy, June 1988."
After all these conversations, Ressler came to a stark conclusion: There is no one kind of serial killer. "They say there are no stupid questions. But that is," Ressler told Seattle PI. "What is a serial killer like? It's like saying what is a journalist like or what is a policeman like or what is a minister like."
While at the FBI, Ressler also developed Vi-CAP (Violent Criminal Apprehension Program), a database used to find patterns between homicides.
Ressler retired in 1990, but continued to steep himself in psychological profiling as a consultant, working with police units in London and Johnnesburg. Ressler reflected on his career in the autobiography Whoever Fights Monsters: My Twenty Years Tracking Serial Killers for the FBI.
For a Mindhunter devotee, some of the main points in Ressler's book will seem familiar. For example: People who go on to become serial killers often exhibit deviant behavior in childhood. “There is no such thing as the person who at age 35 suddenly changes from being perfectly normal and erupts into totally evil, disruptive, murderous behavior. The behaviors that are precursors to murder have been present and developing in that person's life for a long, long time — since childhood,” Ressler writes.
For more in-depth, clinical findings, check out the textbook Ressler co-authored with Douglas and Dr. Ann Burgess, Sexual Homicide: Patterns and Motives. Beware: jargon follows.
Like Tench, Ressler as married — but his wife's name was Helen. It appears Mindhunter wants to separate Tench's home life (and his potentially murderous son) from Ressler's. Ressler and Helen had a son and two daughters.
Ressler died in 2013 at the age of 76 of Parkinson's Disease. To the FBI, he'll forever be "the stuff of legend," as Douglas wrote in his obituary.