BEIJING, Feb. 19 (Xinhuanet) -- A large collection of documents and items linked to the 1963 assassination of former U.S. President John F. Kennedy was released on Monday for the first time in decades, media reported.

    Dallas County District Attorney Craig Watkins presented the items at a news conference Monday. Watkins said they were locked in an old safe in a Dallas courthouse for nearly two decades and that investigators had made him aware of them after he took office in 2006.

    "We decided that this information is too important to keep secret," Watkins said.

    However, how much of the cache is relevant, important or even genuine has yet to be determined, he added. No outside experts have examined the materials, and most have not been reviewed by Watkins' staff.

    One potentially controversial item is a transcript of an exchange between assassin Lee Harvey Oswald and Oswald's killer Jack Ruby, in which they discuss killing Kennedy to halt the mafia-busting agenda of his brother, Attorney General Robert Kennedy. Ruby shot Oswald two days after the president's death.

    One theory about the transcript was that it was part of a movie script Henry Wade, the district attorney at the time of the assassination, was working on with producers.

    Wade signed a contract for a movie deal, although the film was never made. He died in 2001.

    The items also include Ruby's brown leather gun holster, two brass knuckles found on Ruby when he was arrested, personal letters from Wade and a movie contract Wade signed.

    (Agencies)