Need help in Fallout 3 please?

So I'm at the point where I'm trying to escape vault 101, and I'm trying to find the Overseer's office, but I got lost, and found Butch, and it said "Pickpocket butch" and when I tried to take his switchblade, he came running after me with it cutting me up until I die. HE WON'T LEAVE ME ALONE. I keep dying and I can't even look for a healthpack without being knifed to death every five seconds. SO could someone please tell me how to get rid of him? (I'm completely out of weapons, I think I dropped my BB gun on the ground by mistake.) Thanks, it'll help A LOOTTT.