In 1966, Giancana was forced to step down as Mafia boss because he refused to share the profits of his Latin American gambling operations. This was a major violation of Mafia protocol and reflected Sam’s greed.
Another aspect of his behaviour that worried the mob was Sam’s excessively high-profile lifestyle, hobnobbing with Hollywood stars and popular entertainers like singers Phyllis McGuire and Frank Sinatra. He had also been put under close surveillance by the FBI for serious legal problems.
Exile and Assassination
The dethroned Giancana spent the next seven years (1967-74) in exile in Cuernavaca, Mexico, until the Mexican government capitulated to US Justice Department pressure and deported him to the United States.
Giancana was meant to appear before a Senate committee investigating CIA and Mafia links to kill Castro. Whoever decided to carry out an assassination plot on the former Mob King did so to perhaps insure that Sam didn’t reveal anything too incriminating on his return to Chicago.
On 19 June 1975, in the basement of his home in Oak Park, Illinois, an unknown assassin shot Giancana in the head seven times with a silenced .22 calibre handgun. He was found with a wound to the back of his head and six bullet holes in a circle around his mouth. Some suspect the CIA was responsible, others the mob carried out the act with its tradition of omerta – the vow of silence adhered to by all mob members.
CIA Director William Colby was quoted as saying, "We had nothing to do with it."
In fact many researchers believe that Giancana's onetime friend and Chicago Mafia boss, Joseph "Joey Doves" Aiuppa ordered the hit on the disgraced "Momo" because he had become too talkative. Aiuppa may have feared Giancana would reveal everything he knew about Chicago mob operations.
Giancana has been the subject of many biographies. One of them, ‘Mafia Princess’, was written by his daughter Antoinette and filmed as a TV movie starring Tony Curtis as Giancana.