CNN — A military jury on Monday will begin confronting the second phase of the court-martial of Maj. Nidal Hasan: whether he deserves to die for the massacre at his hands four years ago on this sprawling U.S. Army base.
The Army Medical Corps officer was convicted Friday on all 13 counts of murder and 32 counts of attempted murder in connection with the November 5, 2009, shooting rampage at a Fort Hood deployment processing center. The incident occurred about a month before Hasan was to deploy to Afghanistan.
On his own initiative, Hasan admitted early in the court-martial, "The evidence will clearly show that I am the shooter." He has also indicated a willingness to die as a "martyr."
"It's not unlikely he will get his wish," said Eugene Fidell, a military law expert, and professor at Yale Law School. "Given the number (of murders) and gravity that he's been found guilty of, he has to be considered a real viable candidate not only for a death sentence, but also to have it carried out."
The panel of 13 senior officers is expected to hear two or three days of testimony in open court during the sentencing phase.
Military officials say prosecutors could present up to 16 witnesses, including a liaison or family member for each victim killed in the attack. They will describe the impact the shootings had on their lives, part of the "aggravating" evidence the prosecution will use to try to demonstrate why Hasan deserves lethal injection.
During the nearly three-week trial phase, military prosecutors called 89 witnesses and submitted more than 700 pieces of evidence.
Unclear is whether Hasan himself will now present testimony or speak on his behalf. He serves as his own attorney and has so far refused to put on a defense in court.
The American-born psychiatrist of Palestinian descent has the opportunity to offer "mitigating" evidence that could persuade the panel to spare his life.
"All criminal trials -- whether civilian or military -- depend on an adversarial system," said Richard Dieter, executive director of the Death Penalty Information Center. "Where there is too much agreement between opposing sides, or where the defendant refuses to put on a spirited case, does not always lead to a true result. Hasan may be setting himself up for a death sentence. The question is whether this military jury will accommodate him."
The defendant has expressed frustration throughout the proceedings that Judge Tara Osborn, an Army colonel, would not let him argue "defense of others" -- that Hasan carried out the shootings to protect the Afghan Taliban and its leaders from U.S. soldiers set to deploy there.
Through his civilian attorney, Hasan in recent days leaked selected documents to the media, including a mental health evaluation conducted by an earlier, separate military panel to determine whether Hasan was fit to stand trial.
"I don't think what I did was wrong because it was for the greater cause of helping my Muslim brothers," he told the panel, according to pages of the report published by The New York Times.
He also said, according to the documents: "I'm paraplegic and could be in jail for the rest of my life. However, if I died by lethal injection, I would still be a martyr."
That creates an unusual dynamic in what has already become a very unusual case.
"The U.S. military is not used to this kind of defendant, who apparently wants to die for his crimes. It might take a terrible weight off the jury -- if the inmate wants death, they may say, 'we'll accommodate.' It lessens the burden," said Dieter. "On the other hand, the military by its nature, and in this time of war, sees a lot of death. They may not desire to add to it and give (Hasan) what he may want. His wishes might have a reverse effect."
History may not be on Hasan's or the government's side. The last military execution was in 1961, and only five servicemen sit on death row at Fort Leavenworth, Kansas. Three are African-American, two are white.
President Bush signed a death warrant in 2008 for Ronald Gray, a former Army specialist convicted in the military system of several spree killings. His scheduled execution was stayed, and the case remains under appeal.
The military has its own legal standards and procedures when trying and appealing capital cases. The U.S. Supreme Court gets the final say, if any petition reaches that far. Of the 11 military death sentences that have completed direct appeal, nine (82%) have been reversed.
"The military is a community of solidarity, a brotherhood and sisterhood, all to its own," said Teresa Norris, a Columbia, South Carolina-based defense lawyer who represents an Army soldier on death row. "There is a real reluctance to execute fellow soldiers unless it's absolutely the worst kind of case and this is the only way."
That may be especially true for murders committed in an overseas military theater. But Hasan's self-confessed rampage against innocents on a domestic military base will be an important consideration for the panel considering his fate.
Some military law experts say multiple victims play a key role in whether service personnel are prosecuted for capital crimes. Army Staff Sgt. Robert Bales pleaded guilty last month to killing 16 Afghan civilians in Kandahar in 2012, thereby avoiding the death penalty.
Procedures were revised significantly in 1984 after a military appeals court concluded application of the death penalty in that venue was unconstitutional. That led to even fewer capital cases moving forward.
Osborn is likely to instruct the military panel to ignore any direct pleas from Hasan that he be given lethal injection, but to decide punishment only on the facts and testimony presented, in accordance with the law.
"His wishes have little to do with this," said Fidell. "The jury has to be unanimous. But you can have a hold out, you could have a number of holdouts. ... It's very hard to handicap what happens next.