Another possible culprit was the Mafia, in retaliation for the increasing pressure put upon them by Robert Kennedy (who had increased by 12 times the number of prosecutions under President Dwight Eisenhower). Documents never seen by the Warren Commission have revealed that the Mafia was working very closely with the CIA on several assassination attempts of Fidel Castro. Frank Sinatra has been accused of being a "go-between" for the Mafia and the Kennedys. In addition, allegedly the Mafia had funneled thousands of dollars to the Kennedy presidential campaign through back channels, supposedly in exchange for influence in the White House; in one instance, the money was supposedly used to pay off county sheriffs in the state of West Virginia so that the published slate of local candidates included Kennedy for the West Virginia primary, despite the fact that the White House does not have direct and immediate authority over sheriffs in West Virginia. It is also theorized that the Chicago mob helped fix the election returns in the city so that Kennedy would win Illinois' electoral votes, partly as a favor to JFK's father, Joseph Kennedy, and that they later felt betrayed by the pressure put upon the Mob by the Kennedy Administration. Judith Campbell Exner, as described in her book My Story in 1977, was having an affair with Jack Kennedy and Sam Giancana and was used to send money back and forth between the mob and the campaign. Teamsters Union president Jimmy Hoffa, and mobsters Carlos Marcello, Sam Giancana, Johnny Roselli, Charles Nicoletti and Santo Trafficante Jr. (all of whom say Hoffa worked with the CIA on the Castro assassination plots) top the list of House Select Committee on Assassinations Mafia suspects. Carlos Marcello allegedly threatened to assassinate the President to short-circuit his younger brother Bobby, who was serving as attorney general and leading the administration's anti-Mafia crusade. In a documentary titled, "The Murder of JFK: Confession of an Assassin" (1996) James Files claims that he assassinated Kennedy and that Johnny Roselli and Charles Nicoletti were also present at the assassination on the orders of Sam Giancana. He is currently serving a 30-year jail sentence for the attempted murder of a policeman.