Over nearly two decades, Dennis Rader murdered at least 10 people in the Wichita, Kansas area under the pseudonym BTK ('Bind, Torture, Kill'). But despite his repeated taunts to the police and media, investigators were unable to hone in on a suspect.
For Jeffrey Dahmer, it was watching certain movies. Dennis Rader, known as the BTK Killer, set the mood by pretending he was a spy. Ted Bundy liked drinking alcohol before some of his slayings. Not every serial killer has a signature routine, but some of them do engage in some sort of ritual or preparation before a killing.