Guards at the National Archives told the FBI that Berger was observed stuffing his socks with handwritten notes about files he reviewed that were going to the Sept. 11 panel, the News said.

Since the news broke on Monday that Berger was the subject of a criminal investigation over the stolen docs, his lawyer Lanny Breuer has repeatedly told reporters that claims Berger stashed secrets in his socks were "ridiculous."

Guards also told investigators that Berger repeatedly asked to be left alone so he could make private phone calls. If Berger did make any calls from the top secret National Archives reading room, investigators will want to check his cell phone records to see whom he was contacting, and whether he was discussing the purloined documents.

Any calls to ex-President Clinton, who had dispatched Berger on the mission in advance of his own 9/11 testimony, could have staggering implications for the Democratic Party.

When Clinton testified before the 9/11 Commission on April 9, he was accompanied by Berger and his longtime damage controller, Bruce Lindsey.

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