Ruby's motive for killing Oswald remains obscure. There is evidence to suggest that he and Oswald were acquainted with one another. Some evidence also leads to the speculation that Ruby knew Dallas police officer J.D. Tippit, whom the Warren Commision concluded Oswald killed early in the afternoon on November 22, 1963, shortly after having presumably assassinated President Kennedy.

Ruby seems to have been present in a number of key places on the day of President Kennedy's assassination. Witnesses have alleged that Ruby was at Dealey Plaza both before and at the time of the assassination. He was also seen at the Parkland Memorial Hospital while doctors there were vainly attempting to save the president's life. Ruby also elbowed his way into a news conference given by Oswald at police headquarters after midnight that night. All these reported appearances have led reasearchers to suppose that Ruby was somehow involved in the death of the president.

Jack Ruby was in charge of making it look like Lee Harvey Oswald had killed the president. Orders given to him by the mob were to do whatever you must do to set Oswald up. Ruby even followed Oswald after the assassination and shot Officer J.D. Tippit to make it look like Oswald had shot the cop. He was supposed to also kill Oswald at this time and make it look like the cop shot back at Oswald. In fear of being murdered by the mob for not having properly carried out their orders, Ruby shot Oswald that fatal night to make sure Oswald did not talk. Ruby knew he would go to jail but would have been murdered anyway by the mob. Ruby suddenly died of cancer on January 3, 1967. Some researchers remain unsatisfied that Ruby died of "natural causes - raising suspicions that Ruby had been injected with cancer-producing cells or that he had been subjected to heavy doses of cancer-causing X rays.

Communist fanatic kills the President. American fanatic kills the commie. Case closed. RFK knew it wasn't anywhere that simple. Sam Giancana had been overheard by the FBI since early 1961 claiming again and again that he had been double crossed by Jack Kennedy. Four and a half years later, as Bobby Kennedy was successfully running on the Democratic ticket for the upcoming Presidential elections, he was shot by a foreign dissident in a mob-controlled hotel. Again, according to Chuck Giancana's theory, it was just another grudge that Momo ached to settle to his personal satisfaction. Momo described the assassination plot to Chuck afterward claiming it had taken months to mastermind, dozens of men were involved, and, as he quotes Momo, "Richard Nixon and Lyndon Johnson knew about the whole damn thing."

The Mafia theory requires a deeper look into the policies of Kennedy and his Attorney General and brother, Robert. The Kennedys took a much more aggressive stance against organized crime than previous presidents. Robert Kennedy had earned the enmity of Teamster's Union boss Jimmy Hoffa, as well as other mafia members, during his probes and racketeering prosecutions.

The mob also had a Cuban connection. Before the Castro revolution, U.S. mobsters had a lucrative stake in the Hanava casinos and were doing whatever they could to get it back. Mafia families funnelled money to the Cuban exiles, knowing their payback would come with Castro deposed. It's rumoured that the CIA employed mob hitmen to do away with Castro. La Cosa Nostra was understandably irritated at the shabby treatment they received in return from the Kennedys. If rumours that JFK shared a mistress with mobster Sam Giancana are true, perhaps jealousy had something to do with Kennedy's death.

Three weeks before the assassination, Jack Ruby, a small-time mobster, called Nofio Pecora, Marcello's chief aide. Ruby, who had suddenly come into a great deal of cash on November 22, 1963, said later that he was "framed into killing Oswald." After the hit on Kennedy, Marcello let it be widely known throughout the mob world that he had done the hit. He told Jimmy Hoffa through a mob lawyer "You tell him he owes me, and he owes me big." Hoffa rewarded Marcello with $3.5 million from the Teamster's pension fund for a French Quarter hotel project. The House Select Committee on Assassinations (1979) concluded that the Mafia pulled the job. Robert Kennedy blamed Marcello for his brother's death. Ironically, RFK's 3 year prosecution of Marcello ended the day JFK was killed - Carlos Marcello was acquitted in a deportation case November 22nd by a jury in New Orleans.

Oswald had connections to the Soviet Union, Cuba, and the mafia but Ruby was only connected to the mafia. That makes a mafia conspiracy the only plausible one. Prosecutor Jim Garrison of New Orleans (Oliver Stone's source) pointed his finger at everyone except Marcello. It was as if he were Marcello's agent of disinformation (not too surprising given that Garrison hired David Ferrie as his investigator and defended Marcello under oath). Of all the pro-active false leads that Marcello and Ferrie planned, the Cuban connection was the most fruitful. Oswald, who was anti-Castro, was encouraged to join a pro-Castro group, distribute their literature and get this to the notice of the police. An Oswald impersonator signed into the Cuban (and Russian) embassy in Mexico City shortly before the assassination. The supposed Oswald-Cuban connection caused RFK to interfere with the assassination investigation because he did not want the secret that the Kennedys had tried to assassinate Castro to come out. Marcello walked free.