Mindhunter: Inside the FBI's Elite Serial Crime Unit

by John E. Douglas

Behavior reflects personality. It isn’t always easy, and it’s never pleasant, putting yourself in these guys’ shoes—or inside their minds. But that’s what my people and I have to do. We have to try to feel what it was like for each one.

C. Auguste Dupin, the amateur detective hero of Edgar Allan Poe’s 1841 classic “The Murders in the Rue Morgue,” may have been history’s first behavioral profiler.

I was interested in the age-old question of whether criminals are born or made. Though there is still no definitive answer and may never be, listening to Kemper raised some fascinating questions.

The three most common motives of serial rapists and murderers turn out to be domination, manipulation, and control.

the normal common-sense assumptions, verbal cues, body language, and so on that we use to size up other people and make instant judgments about them often don’t apply to sociopaths.

Modus operandi—MO—is learned behavior. It’s what the perpetrator does to commit the crime. It is dynamic—that is, it can change. Signature, a term I coined to distinguish it from MO, is what the perpetrator has to do to fulfill himself. It is static; it does not change.

The difference is, the mental-health professionals start with the personality and infer behavior from that perspective. My people and I start with the behavior and infer the personality from that perspective.

(I’ve often joked that if you have an offender with multiple personalities, I’ll let the innocent personalities go as long as I can lock up the guilty one.)