Anyone seriously interested in the Lincoln County War in New Mexico, the murders of John Tunstall and Alexander McSween by the Dolan-Riley freebooters and their hired guns including Sheriff Brady, and the story of Billy (born Henry McCarty in NYC, later Henry Antrim, best known as William Bonney) should read "Violence in Lincoln County, 1869-1881," by William A. Keleher, Univ. New Mexico Press.

The war arose from a dispute over insurance money of Emil Fritz, a mercantilist. The murder of mercantilist-rancher John Tunstall started a chain reaction of murders. Col. N. A. M. Dudley marched U. S. troops into Lincoln County and for some reason (a payoff?) sided with the Dolan-Riley gang. Charges were brought against Dudley by Lew Wallace, and included the charge that the soldiers, assisted by a gang of armed outlaws, killed Alexander McSween and set fire to his ranch house. Dudley and a group of soldiers had previously entered Tunstall's store and plundered it of more than six thousand dollars of goods.
Some 150 witnesses were to testify against Dudley. The case dragged on---.

Billy Bonney's downfall really ensued from his employment by Tunstall, McSween (and John Chisum) and his loyalty to them; following the murders of Tunstall and McSween, his progression toward outlawry was inevitable.   

Billy was offered a full pardon by Gov. Lew Wallace for his testimony against the murderers of Houston Chapman, a lawyer who was trying to reform conditions in Lincoln County. Billy saw the killing (1879). The murderers escaped, and the pardon was never acted upon.

Later in 1879, several court cases arising out of the Lincoln County War were coming up. Billy, loosely guarded, was waiting again for pardon for killing Sheriff Brady, the murderer of Tunstall. The wait was protracted. Billy, tired of waiting, mounted a horse and rode away, while the guards watched but did not attempt to stop him.

Some contributors to this thread, knowing absolutely nothing about Billy Bonney or the conflicts, in the courts as well as in killing and arson, that led to the Lincoln County War and court cases that lasted for years, parrot nonsense or invent their own fictions.

Lew Wallace was a successful novelist, but hopeless as an administrator; a ditherer who seldom took action.