Updated

Prosecutors rested their death-penalty case against Al Qaeda terrorist Zacarias Moussaoui on Thursday after a former FBI agent testified that investigators might have been able to hunt down Sept. 11, 2001, hijackers if the defendant had confessed before the attacks.

When Moussaoui pleaded guilty last year, he gave details that could have helped identify 11 of the 19 hijackers if he had been forthcoming when he was arrested in the month before the attacks, former agent Aaron Zebley said.

After Zebley's testimony, U.S. District Judge Leonie Brinkema held a closed hearing and sent the jury on a half-hour break. Leaving the courtroom, Moussaoui made clear he intended to take the stand in his own defense.

"I will testify, Zerkin, whether you want it or not," he said, referring to one of his lawyers, Gerald Zerkin. Moussaoui has consistently refused to cooperate with his lawyers.

Zebley testified that Moussaoui's admission that he received more than $14,000 in wire transfers from a man using the name Ahad Sabet could have allowed the FBI to go through Western Union, cell phone, calling-card and motor vehicle records, as well as leases, to identify most of the hijackers.

Brinkema's rulings prevented Zebley from explicitly speculating what the FBI actually would have accomplished had it known this information when Moussaoui was arrested in August 2001. But the clear implication was that Moussaoui's refusal to give a timely confession thwarted some of the FBI's best opportunities to prevent or at least minimize the Sept. 11 attacks.

"We could have set about finding the hijackers," Zebley said.

As it was, certain details did not come out until Moussaoui pleaded guilty in federal court in April.

On cross-examination, defense lawyer Edward MacMahon asked why the urgent pleadings of the FBI agent who arrested Moussaoui for an all-out investigation were ignored.

"The FBI has to have a confession ... before anybody listens?" MacMahon asked.

Zebley replied that the arresting agent, Harry Samit, did not know all the details that were later included in Moussaoui's confession.

The defense also argues that it's not relevant to look at what the results might have been if Moussaoui had confessed when arrested, because he had a right to remain silent in the face of interrogation.

Earlier in the trial, Samit said he spent four weeks warning his bosses about the radical Islamic student pilot. He said bureaucratic resistance to a thorough investigation blocked "a serious opportunity to stop the 9/11 attacks."

Moussaoui is the only person in this country charged in the attacks that killed nearly 3,000 people when Al Qaeda flew hijacked planes into the World Trade Center, the Pentagon and a Pennsylvania field.

He pleaded guilty in April to conspiring with Al Qaeda to hijack aircraft and commit other crimes, but he denies a specific role in 9/11. The sentencing trial now under way will determine whether he is executed or imprisoned for life, the jury's only choices.

When Moussaoui pleaded guilty, he confessed his Al Qaeda membership and divulged numerous details of his terrorist plans, including his flight training, his receipt of Al Qaeda money from an individual in Germany, and Al Qaeda's general plans to hijack aircraft and crash them into prominent U.S. targets.

Moussaoui was arrested Aug. 16, 2001, on immigration violations after he aroused suspicion at a Minnesota flight school. He lied to agents and insisted his flight training was for personal enjoyment.

To obtain the death penalty, prosecutors must prove that Moussaoui's actions caused the death of at least one person on 9/11. They argue that he could have prevented or at least minimized the attacks if he had confessed and alerted federal agents to the imminent threat posed by Al Qaeda.

The defense argues that nothing Moussaoui said after his arrest would have made any difference to the FBI because its bureaucratic intransigence rendered it incapable of reacting swiftly to Moussaoui's arrest under any circumstances.

Prosecutors argue that Moussaoui was obliged to tell the truth once he decided to talk to federal agents, and that the jury can consider what might have happened if Moussaoui had confessed.

Meanwhile, the 4th U.S. Circuit Court of Appeals ordered Brinkema to make public copies of certain documents, videos and photographs the day after they are introduced as evidence. Brinkema had been withholding them until the trial's end. The court acted in a lawsuit brought by nine news and reporters' organizations, including The Associated Press.