Osama bin Laden's driver overheard the al Qaeda leader saying he was happy about the death toll in the September 11th attacks and thought the hijacked plane that crashed in Pennsylvania was shot down, according to one of the driver's interrogators.
The evidence by Ali Soufan, a former FBI agent, was meant to support the case by prosecutors at the Guantanamo Bay war crimes tribunal that the driver, Salim Hamdan, was close to al Qaeda's leadership.
Hamdan, a Yemeni father of two with a fourth-grade education, is the first Guantanamo prisoner to face trial before the controversial tribunal at the remote base on Cuba. He faces life in prison if convicted.
He denies the charges against him.
"Bin Laden was happy about the results and he (Hamdan) heard bin Laden say he didn't expect the operation to be that successful," said Ali Soufan, a former FBI agent. "He only thought 1,000 to 1,500 people would perish so he was happy with the results."
Mr Soufan also said Mr Hamdan told him about a conversation he overheard when he was driving bin Laden and his deputy, Ayman al-Zawahiri, after the attacks that killed nearly 3,000 people in New York, Washington and Pennsylvania.
The two men were looking at a magazine which described the flight routes of the September 11 hijacked planes, Soufan said.
"If they didn't shoot that fourth plane it would have hit the dome," Mr Soufan said bin Laden told Zawahiri, according to Mr Hamdan's account.
"I assumed ('the dome' meant) either Congress or the White House," Soufan said. "Hamdan said he did not know what they mean by the dome."
United Airlines Flight 93 crashed in a Pennsylvania field. US officials have never said it was shot down but there was speculation about the issue at the time.
Prosecutors have portrayed Hamdan as a driver and bodyguard for the fugitive al Qaeda leader who had access to the Islamic militant group's inner circle. Defence lawyers say he was just a hired hand in the motor pool who never joined al Qaeda.
Reuters