Sliphammer by Brian Garfield

An Arizona sheriff takes an impossible job: arresting Wyatt Earp

Wyatt Earp rides the train to Tucson alongside his brother Morgan, who makes the trip in the comfort of a wooden casket. Earp comes from Tombstone, along with his two surviving brothers and Doc Holliday, on a mission of vengeance for his murdered kin. They suspect Frank Stillwell of being the shooter, and are not interested in the bandit’s denials. Earp is hardly off the train before he kills Stillwell, and he’s on his way north before the body is cold.

Unfortunately for the Earp gang, Stillwell had friends in high places. The governor issues warrants for their arrest, and sends a pair of lawmen north to Colorado to apprehend them. Jeremiah Tree, a sheriff nicknamed “Sliphammer” for his choice of pistol, is given the unenviable task of arresting Wyatt and his brother Warren. It’s a suicide mission, but Sliphammer is too cool to fear any gunman, legendary or not.