The US-born Muslim has said he acted to protect Islamic insurgents abroad from American aggression, and he never denied being the gunman.
He acknowledged to the jury that he pulled the trigger in a crowded waiting room where troops were getting final medical checkups before deploying to Iraq and Afghanistan. Thireteen people were killed and more than 30 wounded.
It was the worst ever attack on a US military base. The same jurors who convicted Hasan last week had two options: agree unanimously that Hasan should die or watch the 42-year-old get an automatic sentence of life in prison with no chance of parole.
The lead prosecutor assured jurors that Hasan would "never be a martyr" despite his attempt to tie the attack to religion.
"He is a criminal. He is a cold-blooded murderer," Col. Mike Mulligan said today in his final plea for a rare military death sentence.
For nearly four years, the federal government has sought to execute Hasan, believing that any sentence short of a lethal injection would deny justice to the families of the dead and the survivors.
He was never allowed to argue in front of the jury that the shooting was necessary to protect Islamic and Taliban leaders from US troops. During the trial, Hasan leaked documents to journalists that revealed him telling military mental health workers in 2010 that he could "still be a martyr" if executed.
All but one of the dead were soldiers, including a pregnant private who curled on the floor and pleaded for her baby's life.
