On Nov. 22, 1963, President John F. Kennedy was gunned down as he rode in a motorcade through Dallas. That killing, and the subsequent murder of his alleged assassin Lee Harvey Oswald while in police custody, traumatized a nation so intensely that the feeling has never quite faded.
The Warren Commission, a board of inquest appointed by JFK's successor Lyndon B. Johnson, produced a voluminous report to substantiate the official conclusion that Oswald had indeed killed Kennedy and acted alone.
Yet many people found that story difficult to accept.
How could someone who displayed abysmal marksmanship skills in his brief Marine Corps career, manage to hit a distant, moving target with two of the three shots that he fired from a sixth-floor window? What if Oswald was telling the truth when, after his arrest, he said, "I'm just a patsy"? And wasn't it a bit too convenient that Jack Ruby, a nightclub owner with conspicuous organized crime connections, got close enough to Oswald to kill him, before he could talk further?
It didn't help when, in 1979, a Congressional committee that reopened the case concluded that the original investigation had been less than complete, and raised the possibility that JFK had been killed by a conspiracy [source: National Archives].
Yet, to this day, there is no hard evidence of one, despite all the theories and names tossed out over the years. "The reason is, there is [no conspiracy] to leak out," Vincent Bugliosi, attorney and author of "Reclaiming History: The Assassination of John F. Kennedy" told the Dallas Morning News in 2013.
Still, skeptics continue to peruse grainy home movies of the event and study arcane documentation from the investigation, looking for the proverbial smoking gun that will crack the case. Here are 10 theories that offer conspiratorial explanations for what happened, some more believable than others.