Tom Horn was a man of many hats. He was an Army scout, a lawman, an assassin and an outlaw. His name may not be as well-known as that of Billy the Kid or Jesse James, but he was certainly one of the most cold-blooded killers of the Wild West. During the late 1880s, Horn worked for the Pinkerton Detective Agency as a bounty hunter. While he initially seemed like a good fit, his capacity for violence did not go unnoticed. In 1894, he was forced to resign after he was linked to 17 murders. Stripped of his badge, Horn became a killer-for-hire. His typical target was cattle rustlers and he is believed responsible for the deaths of at least 20 rustlers. In 1901, Horn was linked to the murder of 14-year-old Willie Nickell. The teen was the son of a rancher. Horn's guilt remains a subject of debate for historians. Regardless of his level of responsibility, Horn was executed by hanging in Cheyenne, Wyo., on November 20, 1903, the day before his 43rd birthday.