I'd like to think I would have gone right up to him and stopped it while in progress, but in reality I think most of us would have turned and ran out of complete confusion/revulsion. I understand having his first contact going to his father. But at that point, he and his father should have gotten law enforcement involved immediately. Yeah, I can't really blame the grad student for reacting as he did because, quite honestly, I have zero clue how I'd react to seeing something so shocking and horrible and out of nowhere. I'd like to think I'd have stopped it, but I really just don't know. We don't have to deal with these types of things in our everyday lives, and we react to such shocks in weird ways if we are confronted with them. It is, however, shady that nothing happened once he talked to his dad, like Jersey said. Once you have the time to process this you need to tell someone who can do something.