Complex sentence: The day after Bullock's arrival, Wild Bill Hickok died after being shot in the back of the head by Jack McCall, who was later found not guilty by an impromptu camp court and released, after which he promptly left town.
Split into simpler sentences: The day after Bullock's arrival, Wild Bill Hickok was murdered by Jack McCall. McCall was later found not guilty by an impromptu camp court and released, after which he promptly left town.