Even the U.S. Government eventually acknowledged that the 35th President of the United States might have been killed as a result of a conspiracy.
But who benefited from the crime? There are plenty of suspects to go around. Some theorize that Cuban President Fidel Castro might have had a hand in it as a retaliation for the ill-fated Bay of Pigs invasion in 1961 and for other attempts on his life. The Mob (and other types of questionable ethics, such as Jimmy Hoffa) were also no friend of JFK, whose brother, Attorney General Robert Kennedy, made no secret of the fact that he wanted to shut down organized crime. The CIA may even have gotten involved, or so the theory goes, because of ties they forged with both criminal and Cuban groups.
There's no shortage of suspects from the political world, either. The benefits conveyed on Vice President Lyndon Johnson were obvious - such is the thesis of the play MacBird! - and there were suspicions that FBI Director J. Edgar Hoover, theoretically in charge of the investigation, might have had political reasons for doing what was considered at best a less-than-thorough job and at worst a cover-up. Though not a direct beneficiary, JFK's archrival, former Vice President Richard Nixon - who also happened to be in Dallas that day, attending a Pepsi-Cola bottling convention - was put in a much better position to become President, which he eventually did in 1969. And some die-hard conspiracy buffs point out that three of the ships used in the Bay of Pigs fiasco (originally under Nixon's purview) were named Barbara, Houston, and Zapata - names all closely associated with future U.S. President and CIA Director George Herbert Walker Bush.
Regardless of one's personal theories as to who might have done the deed, the crime was still spectacular. Whoever was responsible - he, she, or they - managed to pick off a President of the United States, something that no one had been able to do in over sixty years.