First use of the term "serial killer"

The first documented use of the phrase "serial killer" comes from an article written in 1930 by celebrated German detective Ernst Gennat. In his description of the "Vampire of Düsseldorf" (child murderer Peter Kürten), Gennat dismissed press descriptions of Kürten as a "maniac of almost supernatural powers" or "a creature of sub-human brutality", instead arguing for the plain description serienmörder, or "serial killer".

For many years, credit for coining the phrase "serial killer" was given to (and claimed by) former FBI Special Agent Robert Ressler, one of the founding members of the Bureau's elite Behavioral Science Unit. In his 1992 memoir, Whoever Fights Monsters, Ressler writes that, in the early 1970s, while attending a weeklong conference at the British police academy, he heard a fellow participant refer to "crimes in series," meaning "a series of rapes, burglaries, arsons, or murders." Ressler was so impressed by the phrase that, upon returning to Quantico, he began to use the term "serial killer" in his own lectures to describe "the killing of those who do one murder, then another and another in a fairly repetitive way."

While it’s possible that Ressler thought up the term independently, subsequent research has traced its origins to much earlier sources. The authoritative Oxford English Dictionary, for example, cites a 1961 piece by the German film historian Siegfried Kracauer, who, discussing Peter Lorre’s character in Fritz Lang’s M, writes that “Beckert denies that he is the pursued serial murderer.” Five years later, the term appears repeatedly in the book The Meaning of Murder by British writer John Brophy. Speaking of Jack the Ripper, for example, Brophy describes him as “still the most famous of all serial murderers.”

Ernst Gennat was an important figure both in the history of criminal investigation and the culture of Weimar-era Germany. As the head of Berlin's Zentrale Mordinspektion ("central murder inspectorate"), he modernized and formalized many of the procedures related to homicide investigations. He organized his department like a military unit, with three investigation teams, each led by a pair of detectives supported by five or six constables, a stenographer and a dog handler. These teams could call on a separate forensic unit, who operated the custom-built M-auto ("murder wagon") – a mobile forensics lab that could be quickly set up at the scene of a crime.

As the head of the unit, Gennat made frequent appearances in the press. He was an articulate, highly intelligent man, well known for his patient, methodical approach to investigations, his photographic memory and his psychological insight. Fictionalized versions of Gennat began appearing in film and print while he was still alive, most notably the character of Inspector Karl Lohmann in Fritz Lang's 1931 film M.