- Jeffrey Dahmer was a prankster in high school. Pulling pranks became known as "pulling a Dahmer."
- Charles Manson was only five feet and two inches.
- Ted Bundy used to work at a suicide hotline.
- Ed Kemper turned himself in.
- Richard Ramirez would only enter homes where the door/window was unlocked. He believed if the door was locked he was unwelcome.
- Jeffrey Dammer gave people in his apartment building sandwiches believed to be made from his victims.
- Manson wrote a song for the Beach Boys, "Never Learn Not to Love," which is credited to drummer, Dennis Wilson. Manson wrote songs as an aspiring musician which have been covered by many bands after his arrest.
- Ted Bundy saved a child from drowning.
- Dennis Raider worked for a security company. During the height of his killings in Kansas he was installing home alarms, though most people were putting alarms in because of his murders.
- H.H. Holmes is one of the first serial killers in modern American history. He is believed to have sold some of the skeletons of his victims to medical schools. There is a conspiracy theory that he is Jack the Ripper, the first serial killer in modern history.
- Kemper narrated books on tape while in prison.
- Manson was to get married in prison in 2014 to a 26-year-old woman, he was 80, The marriage was cancelled after it was discovered it was a plot to make money.
- It is unknown how many murders Bundy committed. It could 361 or 136. Authorities knew he had committed 36 murders, but Bundy added the number one and gave no further hints.
- John Wayne Gacy met First Lady Carter and had secret service security clearance as a result of his work with children.
- The Freeway Phanton, D.C.'s own serial killer in the early 1970s, raped and stranded six women leaving their bodies near the freeway. The Freeway Phantom has never been caught.