Reminds me of the story of two former death camp inmates who had got a hold of one of the former SS Guards. They happened upon an young U.S. officer. They asked if they could borrow his sidearm. He accommodated them, lending his .45. They took the former SS man around the corner, a shot rang out. The two former inmates returned, sans guard. They returned the officer's sidearm, and politely thanked him.
Rough justice, but justice truly.
And actually fairly merciful, unless they simply shot him once in the groin or stomach, given how people were treated in those camps.