While Kennedy's murderer was declared soon after the assassination to have worked alone, one insider claimed to Fox News host Tucker Carlson that the Central Intelligence Agency (CIA) was directly involved with JFK's assassination.

Carlson noted that questions about the Kennedy assassination have been circulating since it happened, simply because there were a lot of details that didn't add up or seemed too coincidental and the CIA refused to release its documentation on the killing.

President Lyndon B. Johnson released a report the year after JFK's untimely death declaring that both Kennedy's killer, Lee Harvey Oswald, and Oswald's killer, Jack Ruby, were acting alone. About 50 years later the CIA admitted it had withheld evidence–but why is still publicly unknown. Carlson said that the term "conspiracy theory" was first brought into everyday American lexicon by the media following JFK's assassination due to the many rumors and suspicions flying about. The phrase then–as now, of course–was used to label anything and everything contrary to a government pronouncement–both plausible questions and far-out kookiness–as pure nonsense.

Carlson cited one potentially suspicious circumstance, saying that psychiatrist Louis Jolyon West declared in April 1964 that Jack Ruby was insane after visiting Ruby in jail. West wrote that Ruby was in need of psychiatric hospitalization, even though no one encountering Ruby before had diagnosed him as insane.  West was a contract psychiatrist and mind control expert working for the CIA at the time. He was involved in the CIA MK Ultra program, which gave powerful psychiatric drugs to some Americans without telling them about it. U.S. media has never investigated why a CIA psychiatrist who specialized in uninformed mind control was diagnosing Ruby. Therefore, the reasons behind West's selection remain lost to history.