When Mr. Bush repeated the claim months later  in a 16-word sentence of his 2003 State of the Union address weeks before the Iraq invasion  Mr. Wilson wrote that he was compelled to question publicly whether Mr. Cheney had ignored his findings because they were inconvenient to the case against Iraq.

Even prosecution witnesses have testified that while Mr. Cheney had asked for more information about the accusation that Mr. Hussein sought uranium in Africa more than a year before the invasion, he did not know that Mr. Wilson was sent to investigate. And, witnesses said at trial, he did not learn about the trip until Mr. Wilson began to make his case publicly. This might explain why Mr. Cheney was so intent on debunking Mr. Wilson.

News of Mr. Wilson’s mission, its findings and Mr. Cheney’s supposed role in his assignment first surfaced two months before he stepped forward with his article, in reports that described him only as an anonymous former ambassador. Mr. Wilson decided to reveal himself after concluding that his anonymous account was not being taken seriously enough, according to testimony.

But those earlier reports prompted a quiet scramble by Mr. Libby to figure out who this anonymous ambassador was, who had sent him on his mission and what had happened with his findings. By the time Mr. Wilson came forward, Mr. Libby and Mr. Cheney knew that Mr. Wilson had been dispatched to Africa by the C.I.A. unit where his wife, Valerie, worked. The eventual exposure of her identity as a covert operative set forth the investigation that led to Mr. Libby’s trial this year.

Mr. Libby faces charges that he lied to authorities who were looking into whether, in defending against Mr. Wilson’s accusations, the administration intentionally exposed the identity of Mrs. Wilson to undercut her husband and clear Mr. Cheney. A jury will decide if Mr. Libby misled investigators or, as his defense asserts, lost track of what he said or learned amid a hectic schedule.

White House officials denied several requests for comment about the testimony and the story it generally tells, citing a reluctance to comment on anything involving the trial.

Declassifying and Leaking

Mr. Wilson’s July 6 article was, in Mr. Libby’s view, “a very serious attack.” In his grand jury testimony, which was shared in the current trial, he said the charges amounted to a potentially severe blow to the administration credibility.