As a congressional inquiry discovered in 1975, the CIA hatched numerous plots to assassinate Cuban dictator Fidel Castro during Kennedy's presidency, including an attempt to poison his food [source: Kessler]. Did Castro decide to return the favor? Lyndon B. Johnson harbored such suspicions. In a 1967 phone call to acting Attorney General Ramsey Clark that was secretly recorded, LBJ even described a rumor he'd heard about how Castro had captured plotters against him and tortured them into revealing that they were working for the CIA.
"So he said, 'Okay. We'll just take care of that,'" LBJ said. "So then he called Oswald and a group in, and told them to ... go set it up and get the job done" [source: Holland].
Oswald was involved with pro-Castro activism and even tried to obtain a visa to visit Cuba in the summer before JFK's death. But clear-cut proof of a Cuban role in the assassination has yet to emerge, and in a 1977 interview, Castro himself said that killing Kennedy would have been "absolute insanity," because the U.S. might have attacked Cuba in retaliation [source: Volkman].