Last updated at 09:20 19 February 2008

A batch of old documents linked to the assassination of President John F Kennedy has been found in an old safe at a Dallas courthouse.

They include what appears to be a transcript of a conversation between killer Lee Harvey Oswald and Oswald's killer Jack Ruby.

Scroll down for more...

Death of a president: The fateful shooting of JFK in Dallas, November 1963

Also in the stash were letters reportedly from former District Attorney Henry Wade, the prosecutor in the Ruby trial - as well as official records from the trial, a gun holster and clothing that probably belonged to Ruby and Oswald, the current DA Craig Watkins said.

But the most controversial item is a transcript of an exchange between Oswald and Ruby in which they discuss killing Kennedy to halt the Mafia-busting agenda of his brother, Attorney General Robert Kennedy.

The Dallas Morning News said one theory about the transcript was that it was part of a movie script Wade was working on with producers, for a film that was never made.

The transcript resembles one published by the Warren Commission, which investigated Kennedy's assassination and concluded that Oswald acted alone.

The FBI claims the conversation between Oswald and Ruby - this time about killing Texas Governor John Connally - was definitely a fake.

Connally was riding in the car with Kennedy and was wounded in the attack.

The documents may be a Presidents' Day gift to conspiracy theorists who have long questioned the official U.S. government version that Oswald acted alone when he shot Kennedy on November 22, 1963, as the president's motorcade swept past the Texas School Book Depository in downtown Dallas.

Scroll down for more...

Nightclub owner Ruby subsequently shot Oswald dead at point-blank range two days later as police were escorting their prime suspect.

Ruby died a few years later from cancer.