Charlie Siringo, the "cowboy detective," was the real deal. I've read of his exploits in numerous books and once had his autobiography. (Loaned it to someone and never got it back.)
One interesting episode was when he was hired by the large LX ranch out of Tularosa, New Mexico Terr., to stop a rancher/rustler named Pat Coghlan, and Coghlan's good buddy and compatriot, Billy the Kid, from rustling and butchering LX beef.
Siringo stopped it, but was nearly ambushed by some LX riders. He was saved when his mule slipped on an icy ledge and rolled down into a gulley. Siringo managed to slip away and hide from two gunmen who'd tried to kill him.
Lots of interesting tales of the Tularosa and El Paso areas of that time.
L.W.