It was suspected that Dean O’Banion killed him, as Duffy was last seen getting into a car with O’Banion and one man who authorities later decided was James Monahan, Hymie Weiss’s brother in law, outside of the Four Deuces, an establishment run by South Side leaders Johnny Torrio and Al Capone. That fact and the fact that Weiss’s car was used, inadvertently throwing suspicion on O’Banion’s friend, implies that rather than being a plot to frame Torrio, it was another of O’Banion’s impulsive, spur of the moment decisions. Coming down the street, Hymie Weiss and George Moran saw the cars and detoured to Weiss’s mothers house, where he telephoned the shop asking for O’Banion.