"The most important thing that CBS left out of its statement . . . is that Bill did not vouch for their authenticity to the CBS producer to whom he gave copies of the documents," Van Os said.

"In his gut he has been believing that they are valid," Van Os added. "But he is the first to say, 'I'm not a document examiner. I'm not qualified to give an expert opinion, and I really don't know.' Bill went to pains to make that point to the CBS producer."

CBS declined to respond to Van Os' comments.

Van Os' comments put additional heat on Rather and CBS, who, according to Kathleen Hall Jamieson, director of the Annenberg Public Policy Center, took too long to respond to authenticity questions that cropped up shortly after the documents were aired Sept. 8 on "60 Minutes II."

"Every minute spent asking whether Dan Rather will stay or go is a minute we should spend on something else," she said, noting that the document debate has dominated political news coverage in recent days.

And, Jamieson added, it leaves Rather's future rather uncertain.

"The public will vote with its clickers," she said. "If they see a drop in ratings, he would probably announce his retirement sooner than he probably would have. The problem for Dan Rather is he defended the story after it had been challenged."

In his Monday statement, Rather said, "I find we have been misled on the key question of how our source for the documents came into possession of these papers.

"That, combined with some of the questions that have been raised in public and in the press, leads me to a point where — if I knew then what I know now — I would not have gone ahead with the story as it was aired, and I certainly would not have used the documents in questions," he said.

Rather called it "an error that was made . . . in good faith and in the spirit of trying to carry on a CBS News tradition of investigative reporting without fear or favoritism."

White House spokesman Scott McClellan said the CBS announcement leaves "a number of serious questions that remain unanswered and they need to be answered." He called Burkett "a source who has been discredited in the past" and noted media reports saying Burkett had been in touch with Democratic and Kerry campaign officials.

Van Os confirmed that his client had contacted Democratic and Kerry campaign officials but only to offer a time line based on publicly released documents relating to Bush's guard duty. Van Os said Burkett has not discussed the disputed documents with Democratic officials. He also said Kerry campaign officials never returned Burkett's calls.

However, Joe Lockhart of the Kerry campaign said he did phone Burkett — at the suggestion of CBS producer Mary Mapes.