Murchison, Snr., like almost all oilmen, had backed Johnson for the White House in 1960, and his fears about Kennedy turned out to be justified. The young President made no secret of his opposition to the oil moguls' extraordinary tax privileges, and moved quickly to change them. Murchison and his associates, it turns out, were linked to the assassination saga by a series of disconcerting coincidences.

George de Mohrenschildt, an oil geologist who knew Murchison and had worked for one of his companies, was on intimate terms with alleged assassin Oswald. He would be found shot dead in 1977, an apparent suicide, on the day an Assassinations Committee investigator called to arrange an interview.

Within four days of the assassination, the FBI received a tip-off that Clint Murchison and Tom Webb - the FBI veteran the millionaire had hired at Edgar's suggestion - were both acquainted with Jack Ruby. While they denied it. Ruby had met one of Murchison's best friends, Humble Oil millionaire Billy Byars.

Byars was close to Edgar. They used adjacent bungalows at Murchison's California hotel each summer. The phone log for the Director's office shows that, aside from calls to Robert Kennedy and the head of the Secret Service, Edgar called only one man on the afternoon the President was shot - Billy Byars.

According to Delphine Roberts, Lee Oswald walked into her office sometime in 1963 and asked to fill in the forms for accreditation as one of Banister's "agents." Mrs. Roberts told me, "Oswald introduced himself by name and said he was seeking an application form. I did not think that was really why he was there. During the course of the conversation I gained the impression that he and Guy Banister already knew each other. After Oswald filled out the application form Guy Banister called him into the office. The door was closed, and a lengthy conversation took place. Then the young man left. I presumed then, and now am certain, that the reason for Oswald being there was that he was required to act undercover."

Mrs. Roberts said she was sure that whatever the nature of Banister's "interest" in Oswald, it concerned anti-Castro schemes, plans which she feels certain had the support and encouragement of government intelligence agencies. As she put it, "Mr. Banister had been a special agent for the FBI and was still working for them. There were quite a number of connections which he kept with the FBI and the CIA, too. I know he and the FBI traded information due to his former association...."

Assassination of John F. Kennedy Encyclopedia

Summers places the nexus of the assassination in Cuba, and ironically in the shared interest of Castro and Attorney General Robert Kennedy's wish to clamp down on organised crime. For when Castro came to power he kicked out the mobsters but his initial relations with the USA were good. The Cuban political exiles, though, found great sympathy among the chiefs of the CIA, if not in the White House. The CIA were likely to put their support through the mob but with the failure of the Bay of Pigs the exiles' hatred, like the mobsters, turned on the Kennedies. The FBI at the highest level had little to reason to like the brothers, either: it was Robert Kennedy who made Edgar Hoover admit there was an organised crime problem. But Hoover was not totally corrupt, the Bureau was keeping an eye on the exile activity on the southern coast.

There is evidence that from his military service onwards Oswald was used as a double agent (he was not the only veteran to go to the Soviet Union: they all returned as he did, suggesting a standard course). He was featured in newspapers working both the Fair Play for Cuba committee and speaking for the exiles. He went to Mexico to try to get a Cuban visa, but of the three days that "Oswald" went to the embassy on only one of them was the visitor the real Oswald, and the CIA had tapes which showed this. The FBI opened all his mail sent to the Soviet Embassy, the various committees etc. Everybody knew what was going on. Which leads to the question: so how did the assassination happen? Summers can only make suggestions. Why can we not tell what happened? Summers can tell us how the various agencies screwed up and covered up. They may not have intended it, but the killing of the president was a result of all those conflicting interests.

Anthony Summers' comprehensive work on the assassination of JFK is among the top books on the subject, ranking alongside Gaeton Fonzi's "The Last Investigation." The author's voluminous research brings together the pieces of the jigsaw puzzle in a lucid and rare way. In a nutshell, the anti-Castro Cuban organizations (CRC, Alpha-66, etc.) and their right-wing American supporters (Gerry Patrick Hemming and Interpen, for example), the Mafia (Trafficante, Marcello, Giancana, Roselli), and elements within the CIA (David Atlee Phillips, E.Howard Hunt, Theodore Shackley, David Sanchez Morales, William Harvey, etc.) and their numerous contract agents (David Ferrie, Guy Banister, Lee Harvey Oswald) were collaborating in an effort to assassinate Fidel Castro and reverse the socialist revolution in Cuba. The Mob wanted their gambling casinos back, while the anti-Castro Cubans and the CIA wanted multi-national corporate capitalism back. In a classic case of "blowback", the forces working to destroy Fidel and the Cuban Revolution failed in their efforts and subsequently conspired to destroy the man (JFK) they believed responsible for their failure.

Anthony Summers: There is quite a lot of work being done in the last year or two that whatever the Kennedy administration was doing in conversations through Attwood and Colonel Lechuga, at the same time Robert Kennedy - and presumably the President too - was personally behind a major effort that envisioned the overthrow of Castro in the fall of 1963. Which would involve an internal coup with the death of Castro. After that, massive American backing for which Kennedy's perceived as being (Cuban) democrats as opposed to being right-wing extremists.

I asked Dean Rusk about this, shortly before his death a year or so before. And he told me, yes he learned about the plans for such a coup. They were indeed backed by JFK and understood by his brother and were in charge of it. That he learned of this in 1964 during meetings of the National Security Council. And what can one make of this? One is talking about not a double track, but a double cross? If the Kennedy's were talking peace on the one hand and a full 1963 coup on the other? He said, yes but they did this all the time. And he found that not surprising. He said the Kennedy's work that way. And he said rather cynically, do governments everywhere. In your research in Cuba, have Mr. Escalante and Lechuga gotten a similar picture of double-track, double-cross?

Fabian Escalante: Look, I'm going to answer very briefly. In 1963 McGeorge Bundy designed this new approach towards Cuba. It involved a double track or multiple track. This appeared in documents in the Church Committee. One of the tracks was to strengthen the blockade against Cuba, political pressure, the isolation of Cuba from the continent and also from Western Europe. To destroy through sabotage and external operations all the energy and industrial infrastructure in the country. In 1963 there were two major plans of sabotage proved against Cuba. Two paths, with one objective. To force Cuba to sit down at the negotiating table, but under very disadvantaged circumstances. That's why we never really heard what the possible American agenda would be. We never heard anything... That's why the Cuban government took its time to deeply study the proposal put forth by Attwood.

What could they possible been trying to do by trying to start a dialogue. So they took their time. Here's what happened according to our judgement. The hawks never supported, they didn't understand this strategy, didn't agree. Anything that didn't agree with a new invasion of Cuba, they didn't agree with. We think the hawks felt themselves betrayed. According to our judgement there were two strategies to be followed by the US: (1) from the administration; (2) and one from the CIA, the Cuban exiles, and the mafia - and even they had their own independent objectives. Around that on the part of this latter group, there developed this need to assassinate Kennedy. It seemed to them that Kennedy was not in agreement to the new invasion. That's our hypothesis.

Anthony Summers: Perhaps I didn't make myself clear. The information that's been coming out, new scholarship that Robert Kennedy personally in those weeks heading up to November 22, in the weeks leading up, was behind a detailed plan for the killing, overthrow of Castro, the killing of Raul, key leaders of the revolution. To be followed by massive American support for take over in Cuba by the so-called Cuban democrats. This was a real plan in the works. This is different from, maybe connected with but very specific and different from conversation.

Bryan Burrough’s laudatory review of Vincent Bugliosi’s book on the Kennedy assassination (May 20) is superficial and gratuitously insulting. “Conspiracy theorists” — blithe generalization — should according to Burroughs be “ridiculed, even shunned ... marginalized the way we’ve marginalized smokers.” Let’s see now. The following people to one degree or another suspected that President Kennedy was killed as the result of a conspiracy, and said so either publicly or privately: Presidents Lyndon Johnson and Richard Nixon; Attorney General Robert Kennedy; John Kennedy’s widow, Jackie; his special adviser dealing with Cuba at the United Nations, William Attwood; F.B.I. director J. Edgar Hoover (!); Senators Richard Russell (a Warren Commission member), and Richard Schweiker and Gary Hart (both of the Senate Intelligence Committee); seven of the eight congressmen on the House Assassinations Committee and its chief counsel, G. Robert Blakey; the Kennedy associates Joe Dolan, Fred Dutton, Richard Goodwin, Pete Hamill, Frank Mankiewicz, Larry O’Brien, Kenneth O’Donnell and Walter Sheridan; the Secret Service agent Roy Kellerman, who rode with the president in the limousine; the presidential physician, Dr. George Burkley; Mayor Richard Daley of Chicago; Frank Sinatra; and the “60 Minutes” producer Don Hewitt. All of the above, à la Burrough, were idiots.

Not so, of course. Most of them were close to the events and people concerned, and some had privileged access to evidence and intelligence that threw doubt on the “lone assassin” version. That doubt remains today. Bugliosi himself this year joined us, Don DeLillo, Gerald Posner, Robert Blakey and two dozen other writers on the assassination in signing an open letter that appeared in the March 15 issue of The New York Review of Books. The letter focused on a specific unresolved lead, the discovery that a highly regarded C.I.A. officer named George Joannides was in 1963 running an anti-Castro exile group that had a series of encounters with Oswald shortly before the assassination.

This is obviously pertinent, yet the C.I.A. hid the fact from four J.F.K. investigations. Since 1998, when the agency did reluctantly disclose the merest outline of what Joannides was up to, it has energetically stonewalled a Freedom of Information suit to obtain the details of its officer’s activities. Here we are in 2007, 15 years after Congress unanimously approved the J.F.K. Assassination Records Act mandating the “immediate” release of all assassination-related records, and the C.I.A. is claiming in federal court that it has the right not to do so.

And now your reviewer, Burrough, seems to lump together all those who question the official story as marginal fools. Burrough’s close-minded stance should be unacceptable to every historian and journalist worthy of the name — especially at a time when a federal agency is striving vigorously to suppress very relevant information.