The fate of a convicted U.S. Army psychiatrist hangs in the balance as a military jury on Monday begins to hear evidence on whether to sentence him to death for firing on unarmed soldiers, killing 13 and wounding 31 in a 2009 shooting rampage at Fort Hood, Texas.
The same jury of 13 military officers on Friday convicted Major Nidal Hasan on all 45 charges of premeditated murder and attempted premeditated murder and will now consider his punishment.
Prosecutors are due to put on evidence in the penalty phase of the trial starting at 9 a.m. CDT (1400 GMT). More than a dozen witnesses are expected to testify.
If the jury is unanimous, Hasan could face the death penalty by lethal injection, possibly making him the first U.S. soldier to be executed by the U.S. military since 1961.
Hasan, 42, an American-born Muslim who acted as his own defense lawyer, told mental health evaluators he wanted to become a martyr, and lawyers assisting him said he was actively seeking the death penalty, though Hasan has disputed that claim.
Hasan will continue to represent himself in the penalty phase. After the conviction on Friday, Judge Colonel Tara Osborn offered him yet another opportunity to allow military-appointed lawyers to represent him.
"I've said it before and I'm going to repeat it. I think it is unwise for you to represent yourself," Osborn said, asking him one last time if he still wanted to be his own lawyer.
"I do," Hasan replied.
He was convicted of opening fire on unarmed soldiers on November 5, 2009, weeks before he was to be deployed to Afghanistan. He had admitted in his opening statement to being the shooter, saying he switched sides in what he considered a U.S. war on Islam.
Twelve of the dead were active duty soldiers and one retired. Of the 31 wounded, 30 were soldiers and one a police officer. Hasan was also charged for shooting at another police officer and missing.
The jury must be unanimous in order to impose the death penalty, which would trigger a lengthy process requiring the approval of the Fort Hood commanding general, and later the president of the United States, in order for there to be an execution.
If he is sentenced to death, he would become the sixth man on death row at the U.S. Disciplinary Barracks at Fort Leavenworth, Kansas, a maximum security facility for military prisoners.