When Fidel Castro's Revolutionary Armed Forces routed the U.S.-backed Cuban exiles in the Bay of Pigs fiasco 40 years ago this week, President John F. Kennedy took full responsibility for the defeat. But the contrition of the young commander in chief, while popular with the American people, played poorly among the tens of thousands of Cubans living here in Miami. Many believed the liberal chief executive's refusal to send planes to support the men scrambling for cover at Playa Girón was a failure of nerve, if not a betrayal. And to this day a certain embittered distrust of Washington, born four decades ago, runs deep in Cuban Miami, erupting whenever the federal government (in the person of Janet Reno or farm-belt Republicans in Congress) pursues policies contrary to the agenda of the first generation of el exilio. But the truth is that whatever the disappointment of the Bay of Pigs, Miami's Cuban exiles have never lacked for support at the highest levels of the U.S. government. From the beginning their anti-Castro cause was taken up by senior leaders of the CIA, who encouraged their ambitions to destroy the Cuban regime. For 38 years one of the most powerful of those leaders has guarded a secret about the events leading up to Kennedy's violent death, a secret potentially damaging to the exile cause as well as to the agency itself.

It is possible that Joannides was not presented with Oswald's name prior to the assassination, but the latest declassified records confirm that a half dozen other top CIA officials were aware of the itinerant ex-Marine and interested in his movements. In September 1963, a month after confronting Joannides's assets in New Orleans, Oswald went to Mexico City and visited the Cuban consulate, seeking a visa. He passed through a CIA surveillance program code-named LIERODE. He then visited the Soviet Embassy where his voice was picked up by a telephonic wiretapping program known as LIENVOY. (These recordings of Oswald, seized from the home office safe of Mexico City station chief Win Scott, were hidden from investigators and later destroyed.) Then, in November, after he returned to Dallas, Oswald wrote a letter to the Soviet Embassy in Washington about his contacts with the Cubans and Soviets in Mexico. The letter was opened by the FBI who shared it with the CIA's counterintelligence staff which had responsibility for tracking Soviet defectors.

John Newman, an Army intelligence analyst turned historian, was the first to parse the new records in his 1995 book Oswald and the CIA. "What we've learned since Stone's movie is that the CIA's interest in Oswald was a lot deeper than they have ever acknowledged," Newman wrote. "As Oswald made his way toward Dallas, the reporting about him was channeled into a file controlled by an office in the counterintelligence staff called the Special Investigations Group."

The SIG, as it was known, was the operational office of James Angleton, the first chief of counterintelligence for the CIA, a legendary controversial figure whose exploits inspired the movie The Good Shepherd. Some thought him a charming and brilliant theorist; others thought him a bully and a paranoid menace. "When Oswald shows up in Mexico City," Newman explains, "his file goes over to the Western Hemisphere division which reviews it and sends out a cable to the State Department and other agencies that is -- how can I put it? -- very selective."

This cable, dated October 10, 1963, is no smoking gun. But is one of the key new documents in the JFK paper trail whose significance is not appreciated by the mainstream media or the furious partisans of the JFK chat groups. The cable, not fully declassified until 2002, was sent after a CIA surveillance microphone picked up Oswald's name during his conversations with the Cubans and Russians in Mexico City. "Who was Oswald?" station chief Scott asked headquarters. "We don't know," replied Langley in the cable. The "latest HDQS info," dated May 1962, was that Oswald was returning from the Soviet Union and had matured politically. In fact, that was not the CIA's latest information, as one of Angleton's aides admitted to the Washington Post in 1995. Acknowledging that she helped draft this cable, this aide said in a tape-recorded interview: "I'm signing off on something I know isn't true." What the cable's authors deliberately omitted, among other things, was mention of a September 1963 FBI report on Oswald's encounters with the DRE in New Orleans.

The most senior official to sign off on the inaccurate cable was Tom Karamessines, trusted assistant to CIA Deputy Director Helms. If Helms was a master spy, the man who kept the secrets, Karamessines was the dependable sidekick who helped him do it. Karamessines was also the patron of his fellow Greek American, Miami field man George Joannides.

The interest of these senior officials does not necessarily imply anything more sinister than a bureaucracy's natural tendency to cover its ass. The CIA had ample reason to be monitoring Oswald in late 1963. He publicly supported the Fair Play for Cuba Committee, a pro-Castro group, formally classified as a "subversive" organization by U.S. national security agencies. He attempted to travel to Cuba via Mexico, a signal of intent to violate U.S. law. Naturally, the Agency was paying attention. But for all this interest, no one thought to discuss Oswald with the Secret Service or the Dallas police. Little wonder that when the name of the suspect in the assassination was first heard at CIA headquarters in Langley, "the effect was electric," as one agency official put it, employing a phrase that was censored from public view for more than three decades.

What is clear is that Oswald was the person in whom the agency had taken considerable interest -- and whose interest it took considerable pains to cover up.