The assassination of John F Kennedy in 1963 was an inside job, according to a deathbed confession given to the veteran film director Oliver Stone.

After making his acclaimed film JFK - which was sympathetic to conspiracy theories about the murder - Stone was contacted by a man claiming to have been a former member of the presidential security team.

Dying of cancer, the man wanted to share a secret that he had until then only told his son – that 'somebody from his own team… had fired on the President'.

A former presidential security team member told director Oliver Stone that one of his team assassinated JFK (pictured, moments before his death)

Stone (right, with Kevin Costner on the set of JFK) said he believed the agent because of his use of 'military jargon' and intricate detail

He gave only a code name 'Ron', in reaching out through a series of mysterious letters before the two men eventually met.

Stone said he was naturally skeptical about such a claim, as there have been so many conspiracy theories since Kennedy was killed by two rifle bullets while travelling in an open limousine through Dallas in November 1963.

Lee Harvey Oswald was accused of shooting the president from the sixth floor of the Texas School Book Depository, only to be shot dead himself two days later by a local nightclub owner with connections to the criminal underworld.

Since then there have been question marks over whether Lee Harvey Oswald fired the shots or - if he did it - who was he working for?

There have also been suggestions that at least one of the fatal shots was fired from a nearby grassy knoll.

Lee Harvey Oswald (center) was accused of shooting the president from the sixth floor of the Texas School Book Depository

There have been several conspiracy theories debating what actually happened that day - with everyone from the mafia to a mystery man on the Grassy Knoll blamed for the killing (pictured, a secret service agent jumps to the president's aid after a shot is fired)

Stone, 69, said his doubts about 'Ron' were dispelled. As a former marine in Vietnam, the film-maker was convinced by the 'military jargon' and intricate details within an account that he describes as 'plausible' and 'very authentic'.

He decided to reveal the man's confession for the first time to Matt Zoller Seitz, who is the author of a forthcoming book on Stone, the Oscar–winning screenwriter and director whose classics include Platoon, about the trauma of the Vietnam War.

Asked why Stone waited until now, Seitz says: 'I think it was because he trusted me, and also because both the father and the son have been dead for a while.

'Nobody has ever heard this story. I'm the first person.'

Stone's co-operated with the book by making himself available for interview giving Seitz free access to his extensive archive without any editorial control.

One of the most radical theories about JFK's death claims his wife Jackie (right) killed him

Stone - whose JFK biopic was sympathetic to conspiracy theories - decided to reveal the agent's confession for the first time to author Matt Zoller Seitz (pictured, John F Kennedy with his wife Jackie)

The book reproduces Stone's recollections of 'Ron'. In one passage, he says that he 'didn't have any ulterior motives': 'He came to me through a series of weird letters through post office boxes.

'Everything would go to a PO Box, and he'd locate it from offshore, from Bermuda.'

The scenario he laid out was very practical. It's the way I would do it, if [I] were going to do something like that Oliver Stone

Recalling their meeting in a hotel in Rochester, New York. Stone says: 'He said he didn't want money or recognition. He said something like, "I want you to know this is from my conscience".'

He adds: 'The scenario he laid out was very practical. It's the way I would do it, if [I] were going to do something like that.

'You kill the president, and your cover is security, and if the sniper or snipers who kill the president are hidden in with the guys who are supposed to protect him, guys who have no knowledge of this plot… It makes a lot of sense.

'The scenario he laid out was very practical,' said Stone of his conversations with the agent known only as 'Ron' (pictured, Kevin Costner in JFK's biopic)

'And his memory of it was so technical, filled with military jargon, details about radio communications right after the shots.'

Seitz points out that when Stone served in Vietnam, he 'participated in what he calls coordinated kill zones where you have a rifleman stationed at different locations to catch people in a cross fire in more than one direction'.