when carella finds this out he rushes to teddy's apartment, hoping the killer is not already there. when carella arrives at teddy's apartment he hears shouting and cursing coming from inside. with his .38 in hand, carella enters teddy's room and is immediately faced with a man aiming a .45 right at him. carella drops to the floor the instant he enters the room and shoots the man holding the .45 twice in the thigh. after making sure teddy is okay, carella interrogates the man, finding out that his name is paul mercer and that he was the murderer of all three cops.