Whas this even possible in Fallout 3?

I was going to Tenpenny to detonate the Nuclear Bomb in Megaton and I see a Ghoul named Roy Phillips trying to get in and I try to kill him and die twice and then I through a grenade and it says,"Critical damage to Roy's leg". Then I see him dead with blood splattered and a half leg missing. Then I have to kill him and his followers. But when I kill them I don't see Roy (Only some ghoul with a biker helmet Masters I think?). Is his a glitch or something or can this be done?