[Byte1]

The ONLY way the gun can fire is if the hammer strikes the firing pin or some old ones have the firing pin on the hammer. If the trigger has been modified, YES the gun can fire without pulling the trigger. BUT, only if the hammer is first pulled back. Single action revolvers ALWAYS have to have the hammer pulled back manually.
He may not "intended" to kill or shoot anyone, but he DID shoot and kill someone. That is manslaughter. He still took a life and must stand trial. The manslaughter was NOT justified, although it may be deemed accidental, such as someone accidentally running over a child when backing out of their driveway. I have seen no reports that he "intended" to end a life or even injure someone. Regardless, by ALL accounts he was negligent and there might be a charge of "negligent homicide" or "negligent manslaughter" depending on the local statute. The gun did not aim itself at the victim and certainly did not arm itself. The gun did not go off while laying on a table. It was handled by AB and it fired, regardless of intent.