"Through our review of the records we found a lot of those pieces and filled them in. But not all of the pieces are findable, at least not at this time, and many of those pieces are lost to history," said Tunheim.
But what does the report say about those missing puzzle parts? The board members acknowledge there will be plenty of questions raised because of what they uncovered. More than 30 years after the fact, the board faced continued reluctance from government agencies.
Tunheim said, "One of their first comments was, 'You know, no one has ever been fired here for protecting information.'"
That was at the CIA, where 30 years ago the chief investigator into the assassination was James Angleton, an expert in counter-intelligence.
"As the CIA says today, his records are no longer identifiable as a collection, which means, they don't exist," said Tunheim.
The CIA destroyed those files long ago. But what about the Secret Service files from the agency that was guarding President Kennedy in Dallas 35 years ago? What Judge Tunheim says he learned may raise more questions for those who think a cover-up still exists.
"The Secret Service destroyed records after we were on the job and working. They claimed it was a mistake that it was just by the normal progression of records destruction," said Tunheim.
The board did find enough evidence to conclude that Lee Harvey Oswald was the only gunman. But what about a possible conspiracy behind Oswald? The board says the record is not as conclusive.
"We do not know what forces played upon Oswald...We do not know whether there were people paying him or supporting him," said Henry Gaff of the review board.
In 1964, Oswald's mother told CBS News that her son was an operative in the cold war for the U.S. She said, "I think my son was sent to Russia."
While in Russia, Oswald married a Russian woman, all part of the plan, said Marguerite Oswald.
"I think he had orders from the State Department to marry the Russian girl," said Mrs. Oswald.
However, Tunheim said, "We couldn't find any evidence in the government files on those claims by Mrs. Oswald."
But those were U.S. files. There are files that exist that may shed light on Oswald that the board wants but can't get. They are Russian files.
According to Tunheim, "High levels in the Soviet government knew all about Oswald, and the KGB conducted a very serious investigation to see whether there was any way to see if the Russians or the Soviets could be tied to the assassination."
Judge Tunheim believes those possibly crucial KGB files on Oswald are only a phone call away.
He said, "I think that if President Clinton asked President Yeltsin to turn over to our government in te interest of history copies of the KGB files, we'd get them right away."
In the U.S., the results of the board's efforts are four and a half million pages of documents on the assassination stored at the National Archives outside Washington, enough, they hope, to dispel any thoughts that if there ever was a government cover-up, there isn't one now.
"What we can say to the American people is that there are no longer files being hidden in government files about the assassination of President Kennedy. " Tunheim said.
As a final note, CBS News has learned that the White House is now actively pursuing efforts to obtain those files from the Russian government.
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