Joe LeFors began his career as a drover and cowboy. He became an inspector/detective running down stolen cattle in Wyoming and Montana. Involved in several gunfights recovering stolen cattle, LeFors, on one occasion had his clothes bullet ridden while killing two thieves. In Wyoming, he pursued bandits from two train robberies. The Wilcox and Tipton, Wyoming robberies were done by Butch Cassidy and his Wild Bunch, but the gang was too illusive and LeFors never captured them.

Later, Joe was a U.S. deputy marshal in Cheyenne, WY where he would become famous for documenting a 'confession' from Tom Horn. A boy named Willie Nickell had been killed and LeFors believed Tom Horn was responsible. Some people believe Tom Horn killed the boy, but most do not. In any event Tom Horn was tried, found guilty and hanged. Joe LeFors is buried in the Willow Grove Cemetery in Buffalo, Wyoming.