A new book has claimed that a group of Mafia bosses was behind the assassination of John F Kennedy - and had only called off at the last moment a similar attack on the President's motorcade during a visit to Tampa, Florida, four days beforehand.
Ultimate Sacrifice, which draws on a new trove of recently declassified documents, asserts that Kennedy was plotting a coup to topple Fidel Castro, the Cuban dictator, on 1 December 1963 - a coup that would have been followed by a US military invasion of the island.
Lamar Waldron and Thom Hartmann, the authors, claim the Mafia got wind of the conspiracy and then infiltrated it, before organising Kennedy's assassination on 22 November 1963.
According to the authors, the Mob believed that the federal authorities - then led by Attorney General Robert Kennedy, the President's brother, who was allegedly running the coup plot - would not have pressed an investigation, which might have revealed the plot against Castro.
Three Mafia bosses - Santo Trafficante, Carlos Marcello and Johnny Rosselli - are said to have been behind the assassination, as well as the aborted attempt in Tampa. Lee Harvey Oswald, was a pawn in the conspiracy. The book purports to show new evidence of the Mafia links of the nightclub owner Jack Ruby, who shot Oswald dead.
But critics have pointed to problems with the book's thesis: Robert McNamara, then running the Pentagon, has said he was not informed of any new plan to invade Cuba before Kennedy's death. It is also implausible that the Mafia, itching to get rid of Castro and restore Cuba's once lucrative gambling industry, would have blocked a plot that would have done just that.