David E. Scheim has published two books claiming that the Mafia were responsible for the assassination of John F. Kennedy. He believes that it was organized by Carlos Marcello, Santos Trafficante and Jimmy Hoffa. This theory is based on the idea that the Mafia were angry with both John F. Kennedy and Robert Kennedy for their attempts to destroy organized crime. Scheim's theory was supported by Trafficante's lawyer, Frank Ragano, who published the book Mob Lawyer, in 1994. The theory is also supported by the investigative journalist, Jack Anderson.
G. Robert Blakey, chief counsel and staff director to the House Select Committee on Assassinations from 1977 to 1979, published The Plot to Kill the President in 1981. In the book Blakey argues that Lee Harvey Oswald was involved but believes that there was at least one gunman firing from the Grassy Knoll. Blakey came to the conclusion that the Mafia boss, Carlos Marcello, organized the assassination.
Anthony Summers is the author of The Kennedy Conspiracy. He believes that Kennedy was killed by a group of anti-Castro activists, funded by Mafia mobsters that had been ousted from Cuba. Summers believes that some members of the CIA took part in this conspiracy. In his book, JFK: The Second Plot (1992), Matthew Smith points out that Thomas H. Killam, a man who worked for Jack Ruby, claimed that there was a link between his former employer, Lee Harvey Oswald and the Mafia. He told his brother, "I am a dead man, but I have run as far as I am running." Killam was found dead in an alley with his throat cut in March, 1964.
In October, 1991, Chauncey Holt confessed to John Craig, Phillip Rogers and Gary Shaw about his role in the assassination of John F. Kennedy. He claimed Peter Licavoli, a leading figure in the Mafia in Detroit, had organized the conspiracy and named Charlie Nicoletti, Charles Harrelson and Charles Rogers as the gunmen.
In 1992 the nephew of Sam Giancana published Double Cross: The Story