Dallas County District Attorney Craig Watkins has allowed access to the dozen boxes of investigation materials for the first time since Ruby shot and killed Oswald, who authorities believe killed President John F. Kennedy 50 years ago, CBS News reported Wednesday.
"This is a virtual treasure trove that literally gets into the mind of Jack Ruby," said Dave Perry, a retired insurance investigator who has studied the Kennedy assassination for more than 40 years.
Among the documents is Ruby's lie-detector test and a possible answer to how Ruby was able to enter the Dallas police garage and shoot Oswald.
That question had tainted police officer Roy Vaughn until the day he died, said his daughter, Nancy Kennemar. Vaughn, who had been assigned to guard the garage ramp, died in 2010.
In a memo, then-District Attorney Henry Wade said Ruby told him he was able to slip past Vaughn because "the officer did not see him." Ruby said he didn't even know the officer's name.
Watkins said he hopes the files provide a better view of history, so he is loaning some of them to the Sixth Floor Museum in the former School Book Depository from which Oswald fired the fatal shots.
"I would imagine when a historian has the opportunity to go through all these documents, they will find little nuggets of jewels they can use to give an explanation of the times back in 1963," he said. "It's an opportunity for us to get a better explanation of how times were, not just in Dallas, but in this country."