You’ve probably never heard of Robert Ressier.
The FBI investigator is credited with coining the term “serial killer,” according to an NPR feature on unknown stories .
Ressier, who wrote a book on criminology, spent much of his career researching serial killers.
“There are people that are pretty good at this, and I would consider myself one of them, certainly,” Ressler said in an NPR interview in 1997.
Ressler died earlier this year.
“He went on face-to-face interviews with the most notorious and successful serial killers at that particular time,” Roy Hazelwood, who worked with Ressler at the FBI for more than 20 years, told NPR.