The Happy Face Killer: Part 1 (S05E11)

Keith Hunter Jesperson, born on April 6, 1955, is a Canadian-American serial killer responsible for the deaths of at least eight women in the United States during the early 1990s. He earned the nickname "Happy Face Killer" due to the smiley faces he included in his numerous letters sent to the media and law enforcement. Most of his victims were vulnerable individuals, such as sex workers and transients, with no prior connection to him. Jesperson preferred strangulation as his method of killing, a technique he had previously used on animals as a child. He was ultimately apprehended and sentenced to multiple life terms in prison without the chance of parole.