The Kennedy assassination ... re-entered the spotlight ... Monday, after the Dallas district attorney unveiled the contents of a safe that had been secret for more than 40 years. Inside were clothing worn by Lee Harvey Oswald; a small, tooled leather holster belonging to his killer, Jack Ruby; and piles of typed, old, crackling documents. Perhaps the most intriguing item was what purports to be a transcript of a conversation Ruby had with Oswald at Ruby's Dallas nightclub, the Carousel, in which they plot to kill Kennedy to satisfy organized crime bosses. The trove of material connected to the assassination was collected by the former district attorney, Henry M. Wade, who prosecuted Ruby and continued in office until 1987. Mr. Wade died in 2001. The documents have not been examined by outside experts. Once the material is cataloged and images scanned into computers, it will be donated to a museum and made available to the public. Although his predecessors had chosen to keep the material in a safe on the 10th floor of the Dallas County Courthouse for decades, [Craig Watkins, who became district attorney last year,] said he saw no reason to do so. We decided that this information is too important to keep secret," he said. In addition to the transcript, he displayed two sets of brass knuckles that belonged to Ruby, and a letter from the Federal Bureau of Investigation to the Dallas police chief, contending that Ruby's sister said her family had somehow obtained a police report on the preparations for Kennedy's visit to Dallas.