From Slender Man to Robocop to Freddy Krueger and more, read how some killers were inspired by the gruesome actions of fictional villains. And watch our new video on how a group of real armed robbers were influenced by the criminals in 'The Town.'

Andrew Walsh, deputy chief of the Las Vegas Metropolitan Police Department, on how he used a mannequin as a decoy to catch a suspect in the murders of two homeless men.

Cracking a murder case commonly draws on forensic evidence and eyewitnesses, but occasionally victims themselves—either before they die or after—are playing a role in helping find their suspected killers.

Tommy Ray, a special agent with the Florida Department of Law Enforcement, came up with an idea that would revolutionize cold-case homicide investigations: making a game out of it.

Killers who leave notes at crime scenes or mail missives to police and the press take a big risk. Read stories and watch videos about eight murderers who just had to put it in writing.