A jury of military officers is expected to consider a verdict later on Monday
A US military jury has retired to consider its verdict after the two-week trial of Osama Bin Laden's former driver at Guantanamo Bay.
Yemeni Salim Hamdan faces life in prison if convicted of conspiracy and supporting terrorism.
In closing arguments, the prosecution said he played a "vital role" in the conspiracy behind the 9/11 attacks.
But defence lawyers said he was a low-level employee, who was "not even an al-Qaeda member".
Mr Hamdan, who was captured in Afghanistan in November 2001, has pleaded not guilty and his defence team say he worked for wages, not to wage war on America.
Mr Hamdan has acknowledged working for Bin Laden in Afghanistan from 1997 to 2001 for $200 (£99) a month, but denies being part of al-Qaeda or taking part in any attacks.
He is the first prisoner to be tried by the US for war crimes since World War II.
The jury ended its initial deliberations after 45 minutes on Monday, and will resume on Tuesday morning.
'Guilt by association'
In its closing argument, the prosecution described Mr Hamdan as a loyal supporter of Osama Bin Laden, who protected the al-Qaeda leader knowing his goals included killing Americans.
"Al-Qaeda aimed to literally take down the West, to kill thousands, and they have; to create economic havoc, and they have.
"They needed enthusiastic, uncontrollably enthusiastic warriors, like that accused, right there, Salim Hamdan," said justice department prosecutor John Murphy.
Lawyers for Mr Hamdan said not one witness had testified that Mr Hamdan played any part in terrorist attacks. They questioned the fairness of the trial, which began on 21 July.
"This is a classic case of guilt by association," said Lieutenant Commander Brian Mizer, a military defence lawyer appointed by the Pentagon.
"Mr Hamdan is not an al-Qaeda warrior, he is not al-Qaeda's last line of defence - he's not even an al-Qaeda member," said Mr Mizer.
About 270 suspects remain in detention in Guantanamo Bay.
Among the dozens of other inmates due to be tried there in the coming months are men accused of plotting the 9/11 attacks.
Human rights campaigners have accused the court of operating in a legal black hole.
They and the other accused will be watching the out come of the Hamdan trial closely, correspondents say.