The conspiracy to assassinate John F. Kennedy and the cover-up of the presence of extraterrestrials on earth are the two biggest of the government's "big lies" alleged by so-called conspiracy buffs.

Assuming that a single covert bureaucracy would manage both coverups, it is not surprising that the same people show up in both conspiracies.

Kenn Thomas, author of 'Maury Island UFO: The Crisman Conspiracy,' identifies one such figure as Fred Crisman, a man with a complicated life story involving the UFO subculture, off-beat domestic politics and the JFK assassination. Thomas spoke about his book at the Crash Retrieval Conference in Las Vegas, Nev., on Nov. 14-16. Thomas is also editor of Steamshovel Press (www.steamshovelpress.com), a conspiracy-oriented magazine and website.

Thomas recounted Crisman's central role in the Maury Island UFO encounter of June 21, 1947, which involved the recovery of slag-like material ejected from a crippled UFO off the coast of Washington.