On December 18, 1931, Diamond's enemies finally caught up with him. Diamond had been staying in a rooming house in Albany, New York, while on trial in Troy, New York, on kidnapping charges. On December 17, Diamond was acquitted. That night, Diamond and his family and friends were at a restaurant. At 1:00 a.m., Diamond went to visit his mistress, Marion "Kiki" Roberts. At 4:30 a.m., Diamond went back to the rooming house and passed out on his bed. Two gunmen entered his room around an hour later. One man held Diamond down while the other shot him three times in the back of the head.