The motive for the killing is still debated. McCall may have been paid for the deed, or it may have been the result of a recent lovers quarrel between the two. Most likely McCall became enraged over what he perceived as a condescending offer from Hickok to let him have enough money for breakfast after he had lost all his money playing poker the previous day. At the resulting two-hour trial by a miners jury (an ad hoc local group of assembled miners and businessmen), McCall claimed that he was avenging Hickok's earlier slaying of his brother, which may have been true. A Lew McCall is known to have been killed by a lawman in Abilene, but it is unknown if he was related, and the name of the lawman was not recorded. McCall was acquitted of the murder, resulting in the Black Hills Pioneer editorializing: "Should it ever be our misfortune to kill a man ... we would simply ask that our trial may take place in some of the mining camps of these hills." Calamity Jane was reputed to have led a mob that threatened McCall with lynching, but at the time of Wild Bill’s death, Jane was being held by military authorities.
McCall was subsequently rearrested after bragging about his deed, and a new trial was held. The authorities did not consider this to be double jeopardy because at the time Deadwood was not recognized by the U.S. as a legitimately incorporated town, as it was in Indian Country and the jury was irregular. The new trial was held in Yankton, capital of the territory. Hickok's brother, Lorenzo Butler Hickok, traveled from Illinois to attend the retrial and spoke to McCall after the trial, noting that he showed no remorse. This time McCall was found guilty.
McCall was hanged on 1 March 1877 and buried in the Roman Catholic cemetery. The cemetery was moved in 1881, and his body was exhumed and found to have the noose still around his neck.