Is the Central Intelligence Agency covering up some dark secret about the assassination of John F. Kennedy? For six years, the agency has fought in federal court to keep secret hundreds of documents from 1963, when an anti-Castro Cuban group it paid clashed publicly with the soon-to-be [alleged] assassin, Lee Harvey Oswald. The files in question, some released under direction of the court and hundreds more that are still secret, involve the curious career of George E. Joannides, the case officer who oversaw the dissident Cubans in 1963. In 1978, the agency made Mr. Joannides the liaison to the House Select Committee on Assassinations - but never told the committee of his earlier role. That concealment has fueled suspicion that Mr. Joannides's real assignment was to limit what the House committee could learn about C.I.A. activities. The agency's deception was first reported in 2001 by Jefferson Morley, who has doggedly pursued the files ever since. Mr. Morley, 51, [is] a former Washington Post reporter and the author of a 2008 biography of a former C.I.A. station chief in Mexico. After losing an appeals court decision in Mr. Morley's lawsuit, the C.I.A. released material last year confirming Mr. Joannides's deep involvement with the anti-Castro Cubans who confronted Oswald. But the agency is withholding 295 specific documents from the 1960s and '70s, while refusing to confirm or deny the existence of many others. The deceptions began in 1964 with the Warren Commission. The C.I.A. hid its schemes to kill Fidel Castro and its ties to the anti-Castro Directorio Revolucionario Estudantil, or Cuban Student Directorate, which received $50,000 a month in C.I.A. support during 1963. In the years since Oswald was named as the assassin, speculation about who might have been behind him has never ended.