Replying to Shitty dorm+shitty roommate= :/

so our dorm room sucks, the knob always falls off from the inside and we have to get people to open it form outside. my roommate sucks, hes just a creepy guy and gets very drunk 6/7 nights of the week and does such things as hold us up in the room with broken glass, etc. etc. but his newest stunt is just.... yeah. he goes out for happy hour and comes back around 8 or so after about 20 some beers. hes not very big but can handle a lot of alochol fairly well. but something about him this time just seems off. i go out and come home about 1 or so and something smells weird in the hall. smell gets worse as i get closer to my room. i hear faint knocking. i open up the door and see the most disgusting/embarrassingly shameful image of my young life. my roommate standing there, completely out of it, in his boxers holding the doorknob (which obviously broke off) and.... shit running down his leg. i was not in the mood to deal so i just said "WHAT THE FUCK" and left. because even though he just shit in my room i couldnt stand the awkwardness. so i leave and come back an hour later and campus security is standing in my doorway talking to roommate. apparently he sobered up a bit and instead of having people think he did something, decided that hed call security and blame it on someone else. his story was "someone rand into the room while i was taking a shower and took a shit" (i assume he doesnt remember i saw him). and funny thing is most people will sort of believe his story because less than a week ago someone from some other floor put a piece of shit in front of someones door. so yeah, i hate my life...and am also trying to think of the most incredible, magnificent way to break it to the rest of the floor/him that i know who shit in our room. ideas?