 During that time, Siringo referred to both Tom Horn and Joe Lefors as a friend.On that case, Siringo often coordinated with Tom Horn, who was by that time working for large cattle companies as a stock detective but who also was retained by the Pinkerton Agency on contract to assist in the robbery investigation.Horn was able to obtain vital information from explosives expert Bill Speck that revealed to investigators who the suspects were who had killed Sheriff Josiah Hazen, who had been shot and killed during the pursuit of the robbers.