The next time Mr. Berger went to the Archives, the documents he was given were all marked - and he apparently pilfered those as well.

Over five visits to the Archives on three separate dates, Berger removed up to six copies of an after-action report on the Millennium bomb plot, which was said to be highly critical of the Clinton administration's counterterrorism failures.

At 15 pages per copy, Berger would have taken up to 90 pages of Millennium reports alone - a quantity of material that defies his explanation that he "inadvertently" lifted the papers. Some of the documents were later destroyed, Berger admitted on Monday.

It's not clear whether the Archives kept a full and accurate inventory of the material made available to 9/11 witnesses such as Berger. But the admission by Archives officials that he took documents they didn't even know they had suggests it may be impossible to determine what material has been lost or destroyed.

Editor's note: