Albert E. Horsley, alias Tom Hogan, alias Harry Orchard
Within a few hours of Steunenberg's death, suspicion began to focus on a man who had been in Caldwell only a few weeks, and whose only apparent reason for being there was his self-proclaimed business as a sheep buyer. Yet, there was no appearance that he had purchased any sheep during his stay. He was registered at the Saratoga Hotel as "Tom Hogan," but during the investigation that followed the assassination, he was recognized as a man named "Harry Orchard" who had been a miner in north Idaho in 1899.
Using a pass key obtained from the hotel, a friend of Steunenberg searched Hogan's room and found evidence of what appeared to be the makings of a bomb similar to the one that killed the former governor. Fragments of plaster of Paris like the foundation of the bomb and fish line identical to the trip string attached to Steunenberg's gate, seemed clearly to implicate Hogan, or Orchard as he became known, and he was arrested.
Eventually, James McParland of the Pinkerton Detective Agency, which had been brought into the case by the State of Idaho, secured a confession from Orchard, that Orchard had set the bomb that killed Steunenberg and that the "inner circle" of officials of the Western Federation of Miners had hired him to kill the former governor.
Orchard also admitted he had killed at least seventeen others besides Steunenberg in support of the activities of the Western Federation of Miners in Colorado and Idaho.
Orchard also admitted that his true name was Albert E. Horsley, that he had come to the United States from Ontario, Canada in 1896, and that he had left a wife and daughter in Canada. During his incarceration, he converted to the Seventh-Day Adventist faith, after Steunenberg's widow, Belle, publicly forgave him for murdering her husband.
In 1907, Orchard testified against William D. "Big Bill" Haywood, the secretary-treasurer of the Western Federation of Miners in a trial in Boise.
In 1908, Orchard testified against George Pettibone, an adviser to the Western Federation. Both Haywood and Pettibone were acquitted of the charges against them for allegedly hiring Orchard to kill Steunenberg.
In 1908, Orchard pled guilty to murdering Steunenberg, and was sentenced to be hanged, but the Idaho Commission on Pardons and Parole commuted the sentence to life in prison.
Orchard served forty-six years in the Idaho State Penitentiary, dying in 1954, after having survived all the others who were participants in the Haywood trial.