This episode has a psychopath that self-harms, it is only about half way through the episode that you find this out. He self-harms by stabbing himself with a knife or making others stab him with a knife. It is shown at one point, all the scars on the side of his abdomen. The SI scene is brief and they only really bring the self injury to light near the end of the episode. It is a really good episode, one that throws you for a loop.