A man who claims he assassinated President John F. Kennedy has been moved this week from a high security jail to a less secure one in Illinois in preparation for his release next spring after 36 years behind bars.

James Files, 72, says that he was the man on the grassy knoll back on November 22, 1963, and that he fired the bullet into Kennedy's head that ultimately killed him.

Now, the CIA and other US secret agencies are preparing for scores of conspiracy theories as Files identifies himself yet again as the missing piece of the Kennedy story.

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Confession: James Files (above) says he is the man who assassinated Pres. John F. Kennedy

New claim, again: Files has claimed before that he was in Dallas, Texas on November 22, 1963, firing the shot that ended the life of Pres. Kennedy as he drove through on his motorcade (above)

Files says the other shot that hit Kennedy came from his boss, Charles 'Chuckie' Nicoletti, who was hiding out in the book depository, the same place Lee Harvey Oswald is believed to have been at the time of the shooting.

The Sunday Express reports that Files claims there was a conspiracy between the mafia and the CIA to kill Kennedy. Such claims could lead to Files being called to Washington to give a testimony under oath.

Files was a Vietnam war veteran who was also part of a team that trained a militia for the unsuccessful Bay of Pigs invasion in 1961.

He said that many in the CIA turned against Kennedy when he called for a stop of the secret operation.

Files was kicked out of the military and became the right hand man to Chicago mafia chief Charles 'Chuckie' Nicoletti, who was a hitman for Chicago mob boss Sam Giancana.

Files, who is currently serving time for being an accessory incident and feared Kennedy was going to shut down the agency. He claims that the CIA called in mobsters to carry out a killing in Dallas.

Location: Files says he took his shot from the infamous grassy knoll (seen in the background above)

Files also says that Oswald, who was charged, but then shot dead before he could be tried or convicted in the killing, never fired a single shot.

He described what happened in a new documentary that aired on Newsmax TV, I Killed JFK.

He says he chose the grassy knoll so he could pretend to be a worker at a nearby rail yard, and come and go without being noticed.

Then, as President Kennedy's motorcade approached, he sprung into action.

'I was aiming at his right eye. When I pulled the trigger it was almost like looking from six feet away through the scope,' he explains.

'As I squeezed his head moved forward. I missed and got it right along the temple, right behind the eye. I squeezed off my round. I hit him and blew his head backward. I fired one shot and one shot only.'

He then walked off with no one noticing, not even the two police officers he claims were standing 25 feet away.

Hideout: Files also claims his boss, Charles “Chuckie” Nicoletti, was in the nearby book depository (above), and not Lee Harvey Oswald

Killed before going on trial:: In the end, Oswald (above) was charged with the murder. Oswald denied killing the president but was killed by nightclub boss Jack Ruby before he could go on trial for murder

He did however leave a trinket, biting down on the shell casing that came from his gun.

The documentary claims that casing matches one a young boy and his father found buried in the knoll over 20 years later.

At least one former FBI agent, Zack Shelton, believes Files story, including the location from which he shot Kennedy.

'I have tried to verify Files' story. A lot of that story I have been able to verify,' says Shleton.

But five government investigations since the assassination have determined it was Oswald who shot Kennedy.

Oswald always denied being the assassin, but was shot dead by nightclub boss Jack Ruby before he could go on trial for murder.