Serial killers are terrifying enough as it is, but some have even darker facts about them that send chills down your spine.
Maybe you've heard that the BTK Killer once worked as a home security system installer, which could be how he got access to many of his victims' houses.
Perhaps you're aware that John Wayne Gacy worked at a mortuary in Las Vegas in his youth, long before committing any of his crimes.
Or that The Vampire Killer of Sacramento said he mostly chose his victims based on whatever doors were unlocked when he walked down the street.
It's terrifying, yet so interesting, to learn about serial killers, so tell us: What's the creepiest fact you know about them?
