During the 1920s, Earle Leonard Nelson killed 22 women across the United States and Canada after sexually assaulting them. Born in 1892, Nelson was struck by a streetcar as a child and suffered a trauma to his head, which caused him chronic pain for several years. He may have suffered permanent brain damage from it as well, for he began to display odd behavior afterward. At the age of 16 he was sent to a home for mental defectives after assaulting a child. He escaped from the facility three times and likely committed his first murder in San Francisco in 1926 when he strangled the owner of a rooming house. Over the next several months Nelson repeated the crime as he traveled from California to Philadelphia. Most victims were women who ran boarding houses or advertised rooms in their homes for rent.

Nelson moved to Winnipeg in the summer 1927 and soon committed two murders there. Police inquiries led to a second-hand clothing dealer who reported that a man had come in to barter his clothes and then changed into his new outfit inside the store. A fountain pen he left behind was traced to the home of one of the victims, and Nelson was arrested near the U.S. border. At his trial in Winnipeg, Nelson's lawyers claimed that he was insane, but prosecutors pointed out that Nelson planned his murders and escapes quite carefully. He denied committing murder at all. A jury found him guilty, and he was hanged in January of 1928. The slayings inspired the 1943 Alfred Hitchcock film Shadow of a Doubt.