FBI discussions on Moussaoui at issue

''No," Rolince snapped.

Had he heard other conclusions by Samit about Moussaoui?

''No. What document are you reading?" Rolince demanded.

The document was Samit's report of Aug. 18 ''sent to your office," MacMahon replied.

Called as a government witness, Rolince, a 31-year FBI veteran who retired in October, seemed to be more valuable for lawyers defending the only man charged in this country in connection with the Al Qaeda attacks of Sept. 11, 2001.

Defense objections and rulings by US District Judge Leonie Brinkema barred Rolince from giving what prosecutors wanted most: a long list of investigative steps the FBI could have taken if Moussaoui had admitted when he was arrested on Aug. 16, 2001, all the facts he had purportedly confessed to when pleading guilty in April 2005.

Instead, MacMahon extracted from Rolince more embarrassing reports about the FBI's handling of terrorism intelligence before the attacks.

This was important because, to get the death penalty at this sentencing trial, the government must show that Moussaoui's lies upon arrest prevented the FBI from identifying Sept. 11 hijackers and the Federal Aviation Administration from altering airport security enough to have saved at least one of the nearly 3,000 people who were killed in the attacks in New York and Washington.

The defense contends that the government knew more than Moussaoui about Sept. 11 beforehand and that the FBI was so inept at fighting terrorism that nothing the defendant could have told them would have mattered.

Moussaoui has admitted that he conspired with Al Qaeda to fly planes into US buildings, but contends that he was not part of the Sept. 11 plot. He said he was training as a pilot to fly a 747 into the White House as part of a possible later attack.

When prosecutor David Raskin began reading Moussaoui's confession and asking Rolince how the FBI could have responded to it in August 2001, Rolince started to describe what the FBI ''would have" done.