Conspiracy theorists consider four or five groups, alone or in combination, to be the primary suspects in the assassination of Kennedy: the CIA, the military-industrial complex, organized crime, the government of Cuba, and Cuban exiles. Other domestic individuals, groups, or organizations implicated in various conspiracy theories include Lyndon Johnson, George H. W. Bush, Sam Giancana, J. Edgar Hoover, Earl Warren, the Federal Bureau of Investigation, the United States Secret Service, the John Birch Society, and far-right wealthy Texans. Some other alleged foreign conspirators include Fidel Castro, the KGB and Nikita Krushchev, Aristotle Onassis, the government of South Vietnam, and international drug lords, including a French heroin syndicate.
Jim Marrs, in his book Crossfire, presented the theory that Kennedy was trying to rein in the power of the Federal Reserve, and that forces opposed to such action might have played at least some part in the assassination. According to Marrs, the issuance of Executive Order 11110 was an effort by Kennedy to transfer power from the Federal Reserve to the United States Department of the Treasury by replacing Federal Reserve Notes with Silver Certificates. Actor and author Richard Belzer named the responsible parties in this theory as American “billionaires, power brokers, and bankers … working in tandem with the CIA and other sympathetic agents of the government.”
A 2010 article in Research magazine discussing various controversies surrounding the Federal Reserve stated that “the wildest accusation against the Fed is that it was involved in Kennedy’s assassination.” Critics of the theory note that Kennedy called for and signed legislation phasing out Silver Certificates in favor of Federal Reserve Notes, thereby enhancing the power of the Federal Reserve; and that Executive Order 11110 was a technicality that only delegated existing presidential powers to the Secretary of the Treasury for administrative convenience during a period of transition.