Born in Philadelphia on May 12, 1897, Nelson was orphaned at nine months of age when his mother died of advanced venereal disease. Raised by an aunt whose religious zeal bordered on fanaticism, he was described as "quiet and morbid" during early childhood. At age ten, while playing in the street, he was struck by a trolley and dragged fifty feet; the accident left him comatose for six days, with a hole in his temple, resulting in headaches and dizziness that grew progressively worse. Near the end of his life, Nelson suffered from pain so severe he was sometimes unable to walk.

Aside from headaches, there were other side-affects from Nelson's accident. His moods grew more oppressive, broken up by manic periods in which he took to walking on his hands or lifting heavy chairs with his teeth. He read the Bible compulsively, underlining numerous passages, but also shocked his aunt by talking "smut" and spying on his female cousin as she stripped for bed. When not preoccupied with voyeurism or the scriptures, Nelson spent his time in basements, relishing the solitude and darkness.

On May 21, 1918, Earle was charged with dragging a neighborhood girl into one of those basements, attempting to rape her. In court, it was revealed that Nelson had been called for military service and rejected as insane by the Naval Hospital Board, but he was convicted regardless and sentenced to two years on a penal farm. His third escape attempt was finally successful, on December 4, and Nelson would remain at large until the spring of 1921.

On August 12, 1919, posing as "Roger Wilson," Earle married a young schoolteacher. Their relationship was short-lived, with Nelson's sexual perversions and obsessive jealousy driving his wife to the point of a nervous breakdown after six months. He called upon her in the hospital, and there attempted to molest her in her bed, before the staff responded to her screams and drove him off. Arrested as a fugitive, he staged another break from prison in November 1923.

The next two years of Nelson's life are lost, but sometime in the interim between his flight and reappearance, Nelson made the move from rape to homicide. In sixteen months, from February 1926 to June 1927, he claimed at least twenty-two victims, preying chiefly on widows and spinsters who took in a mild-mannered boarder, impressed by his manners, his smile and the Bible he carried.

On February 20, 1926, Earle rented rooms from Clara Newman, 60, in San Francisco; she was strangled and raped the same day. Following the identical murder of 60-year-old Laura Beale, in San Jose, newsmen began writing stories about "the Dark Strangler," but their suspect remained elusive.

On June 10, Nelson was back in San Francisco, where he raped and strangled Lilian St. Mary, 63, stuffing her body under a bed. Mrs. George Russell was the next to die, in Santa Barbara, on June 26. On August 16, Mary Nesbit suffered an identical fate in Oakland.

California had become too hot for Nelson, and he sought a change of scene, selecting Portland, Oregon, at random. On October 19, Beata Withers, 35, was raped and strangled, her remains deposited inside a trunk. The next day, Nelson killed Virginia Grant and left her corpse behind the furnace in a house that she had advertised for rent. October 21 found Nelson in the company of Mable Fluke; her body, strangled with a scarf, was found inside the attic of her home.

Police in Portland finally identified their man, but finding him was something else, entirely. (Interviews, conducted with his aunt, recalled tales of Earle's handwalking exploits, leading to his being christened "the Gorilla Murderer.") Nelson struck again in San Francisco on November 18, strangling the wife of William Edmonds. On November 24, he strangled Blanche Myers in Oregon City, tucking her body beneath a bed in her rooming house.

As police dragnets rendered the West Coast uninhabitable, Nelson moved eastward, hitchhiking and riding the rails. In Council Bluffs, Iowa, on December 23, he killed Mrs. John Beard, another landlady. Settling in Kansas City for Christmas, he strangled 23-year-old Bonnie Pace, rebounding on December 28 with the double murder of Germania Harpin and her eight-month-old child.

On April 27, 1927, Nelson strangled Mary McConnell, age 60, in his hometown Philadelphia. A month later, in Buffalo, New York, the victim was Jenny Randolph, 35. Moving on to Detroit, he murdered landlady Minnie May and one of her tenants, Mrs. M.C. Atworthy, on June 1. Two days later, he strangled Mary Sietsorr, 27, in Chicago.

Nelson feared police were closing in on him by now, and made a move to save himself that ultimately brought him to the gallows. Crossing the border into Winnipeg, Canada, he rented a room on June 8, 1927, and strangled Lola Cowan, 14-year-old daughter of his neighboring tenants, the same day. On June 9, housewife Emily Patterson was found bludgeoned and raped in her home, her body hidden underneath a bed.

Hoping to cash in on his last crime, Nelson stole some clothing and resold it at a Winnipeg second-hand shop. Spending his cash on a haircut, he aroused further suspicion when the barber noticed dried blood in his hair. Recognized from his wanted poster in a local post office, Nelson was picked up and jailed at Killarney; he escaped after picking the lock on his cell with a nail file, but he was recaptured twelve hours later, as he tried to slip out of town.

Nelson's trial in the murder of Emily Patterson opened in Winnipeg on November 1, 1927. Only two witnesses - his aunt and former wife - were called by the defense in support of Nelson's insanity plea. Convicted and sentenced to die, he was hanged on January 13, 1928. Before the trap was sprung, he told spectators, "I am innocent. I stand innocent before God and man. I forgive those who have wronged me and ask forgiveness of those I have injured. God have mercy!"

In addition to his twenty-two known murders, Nelson was the leading suspect in a triple murder in Newark, New Jersey, during 1926. The victims included Rose Valentine and Margaret Stanton, both strangled, along with Laura Tidor, shot to death when she attempted to defend them from their killer.