Actually it was the guy who stole Butler's car, but he was already on the ground. His 'friend' Mel, who eventually married his widow, had been slowly poisoning him using a heart med that Mel's wife used. He put it in his drink on NYEve and then the guy fainted while he was walking home. He was then run over, but that didn't kill him. The widow didn't know about the heart med, but Mel took some himself and tried to frame her. But then he panicked after Lily visited him and left the hospital. Then the police cornered him and he shot himself after writing a note confessing it all.
A pretty good show tonight. Kept you guessing all the way through.