Over the years, those theories sprawled, and the government made some of its document hoard public.
Trump tweeted his excitement on Wednesday — as he headed to Dallas for a fundraiser — saying it is “so interesting!”
The National Archives sought to temper expectations, warning the most explosive documents have likely already been released, but the deadline of the JFK Records Act, set 25 years ago, could breathe oxygen into some of the many competing theories.
Oswald was a former Marine who moved to the Soviet Union for a few years before coming back to the US. His association with communist elements and brief trip to Mexico City shortly before he appeared in Dallas are of interest for those who plan to sift through the unreleased files.
Here are a handful of the most popular and well-known conspiracy theories about the assassination:
Multiple shooters
The term “grassy knoll” now recalls the theory that Kennedy’s killer was not necessarily Oswald, but instead a man firing from the ground along the route of Kennedy’s presidential motorcade.
Trump world finger-pointing
Trump’s longtime associate Roger Stone is a passionate conspiracy theorist, who now works for the fringe, far-right website InfoWars.
Stone is an advocate for the full release of the files and authored a book pointing the blame for the assassination at Kennedy’s vice president and successor, Lyndon Johnson.
North Carolina Republican Rep. Walter Jones, a leading congressional advocate for the full release of the files, told CNN he spoke with Stone about pressing Trump not to block the disclosure.
And like his friend Stone, Trump himself has tossed out his thoughts on the assassination, pointing during the campaign to Sen. Ted Cruz’s father — without evidence — as someone potentially involved.
CIA involvement
One of the most popular theories, and one featured in popular culture from Oliver Stone’s film “JFK” to Don DeLillo’s novel “Libra,” is the idea the CIA or people associated with the CIA were involved in some way in the Kennedy assassination.
Some theories go far enough to suggest a CIA-affiliated person fired the deadly shot, while others state the CIA or other government agencies had knowledge there would be an attempt on Kennedy’s life and, by not acting, they were complicit in the murder.
Rep. Jones suggested he belongs to the camp that believes there was likely some agency involvement or inaction and said he believes the release could help settle the matter.
“The government owes the American people the truth,” Jones said. “And if you were complicit then so be it. ‘Fess up to it.”
Castro’s revenge
When Fidel Castro led a communist revolution in Cuba, the US recoiled as the ideological brethren of its Cold War enemies found a foothold not far off from its own shores. Kennedy greenlit an operation, known as the Bay of Pigs, early on in his presidency, in a failed attempt to topple the Castro government.
Given the potential motive and Oswald’s communist leanings, one theory posits Castro had a hand in the killing.
Mafia members
One theory pulls away some of the Cold War mystique and the potentially crazed lone wolf idea. Instead, it posits the Kennedy assassination was a mafia hit, although possibly one with CIA complicity.
Kennedy appointed his brother Robert as attorney general, and the younger Kennedy made going after organized crime one of his top priorities. Moreover, Castro’s revolution pushed out elements in Cuba that were friendly to mafia interests.
Kennedy was not the target
Kennedy was not alone in Dallas. First lady Jackie Kennedy was by his side, as was Democratic Texas Gov. John Connally.
The governor also took fire when Kennedy was killed, and one theory says Oswald meant to kill the governor, not Kennedy.
