It was perhaps inevitable that the continuing torrent of JFK assassination conspiracy theories would converge with another irrepressible conspiracy meme, the belief that the U.S. government has long been engaged in a massive cover-up operation to prevent the public from learning about visits to Earth by extraterrestrial beings.
Adding impetus to this theory are early November 1963 memorandums, unearthed by author William Lester through the Freedom of Information Act, in which JFK asked for a review of all intelligence files related to UFOs. The information was sought as part of the preparations for a joint U.S.-Soviet space effort that JFK hoped to initiate, and Lester believed that Kennedy was concerned about the Soviets mistaking UFOs that flew over their country for U.S. spy aircraft [source: Daily Mail].
But in the feverish minds of conspiracy buffs, it's not hard to imagine a cabal of generals or CIA officials dispatching a team of Men in Black to make sure that the president didn't find out about those alien autopsies being conducted at Area 51, or about the clandestine effort to breed a super-race of human-alien hybrids. Oh wait—that's an old "X-Files" episode that we're thinking of. Never mind!