The real story of Sebastiano "Buster from Chicago" Domingo is chronicled in the article and book by celebrated organized crime author David Critchley. See his article in Global Crime journal and his book "The Origins of Organized Crime in America." Buster did exist and Critchley proves it.
Buster from Chicago (d. September 1931 ?) was a pseudonym used for an alleged unidentified Chicago mobster and freelance hitman during Prohibition. Little is known of Buster from Chicago, however government informant Joe Valachi described Buster as a "college boy" in appearance and was known to frequently carry a Tommy gun inside a large violin case. While working with the unknown assassin, Valachi noted his exceptional skill with a wide range of weaponry including pistols, shotguns and machine guns.
Buster is first recorded being brought to New York mafiosi as a gunman with Salvatore Maranzano and, during the Castellammarse War, he was responsible for the deaths of top Masseria lieutenants Alfred Mineo and Steve Ferrigno gunning them down with a 12-gauge shotgun as they walked through a Bronx neighborhood on November 5, 1930. As his accomplices Joe Profaci, Nick Capuzzi and Joe Valachi fled the scene, Buster allegedly ran into an investigating patrolman who had heard the gunfire. In the guise of a frightened bystander, Buster told the officer the direction of the shooting and calmly walked away as the officer rushed to the scene. In another gangland slaying, Buster killed James Catania (or Joe Baker) as he and his wife left a building. Buster was supposedly proud of the fact that, despite the numerous bullets fired, Catania's wife was unharmed.
However, many details of Buster's career have come under suspicion as certain events described in Valachi's testimony have proven inaccurate or exaggerated such as his claim of Buster's killing of Masseria underboss Peter Morello aka "The Clutching Hand" Morello, which would begin the Castellammarse War between Masseria and Maranzano. Yet Morello's death was never ordered by Maranzano, but by members of Masseria's own organization specifically Albert Anastasia and Frank Scalise of Charles "Lucky" Luciano's Young Turks. Furthermore, it is highly unlikely that an unknown person such as Buster could have infiltrated Morello's headquarters and surprised Morello and his associate Giuseppe Periano as they were counting out an estimated $30,000 in cash receipts (while Masseria gunmen Anastasia and Scalise would have come and gone without notice). Although surviving the Castellammarse War, Buster disappeared from New York's underworld soon after. According to Valachi however, Buster wanted to continue fighting against Luciano believing "They'll take us away, one by one.". Fearing Buster could have been recruited by rivals, Luciano and Vito Genovese ordered his death and, in September 1931, he was allegedly killed in a Lower East Side pool hall and his body secretly disposed of. Just as the origins of Buster from Chicago remain a mystery, so too does his ultimate fate.
The identity of Buster from Chicago was revealed by historian David Critchley as Sebastiano Domingo, who was killed in 1933. The identity of Domingo as Buster is confirmed in the books by Joseph Bonanno and Bill Bonanno, the former as another participant in the Castellammare War and the latter his son. Domingo's nickname, according to the New York Times in 1933, was indeed "Buster." His life story, matching the available evidence on Buster from Chicago, is found in the Critchley book "The Origins of Organized Crime in America" and his article from 2006 in the journal Global Crime on the Castellammare War.