UPDATE: The Army psychiatrist defending himself against charges that he killed 13 people in a shooting rampage at Fort Hood, Texas, rested his case Wednesday without calling a single witness.
FORT HOOD, Texas (CNN) -- The Army psychiatrist defending himself against charges that he opened fire on soldiers at Fort Hood is scheduled to begin his defense Wednesday amid questions on whether he will call a single witness to the stand in the death penalty case.
Maj. Nidal Hasan, 42, is being tried on 13 counts of murder and 32 counts of attempted murder in connection with the November 5, 2009, attack at a deployment processing center for soldiers heading to Afghanistan and Iraq.
Here are the five things to know about the case to date:
1. The prosecution's case
Military prosecutors called 89 witnesses and submitted more than 700 pieces of evidence before resting their case, hoping to show that the American-born Muslim had undergone what they described as a progressive radicalization.
They have argued to the jury that Hasan, who was scheduled to deploy to Afghanistan, did not want to fight against other Muslims and believed he had a jihad duty to kill as many soldiers as possible.
Over the course of 11 days, prosecution witnesses painted a horrific picture of the shooting rampage that began inside the deployment center, with a number recounting how the gunman rose from a chair, shouted "Allahu Akbar" -- Arabic for "God is the greatest" -- and fired more than 146 rounds in the room.
Prosecution witnesses called Tuesday described the final minutes of the attack, and a police shootout that ended with the gunman shooting a police officer before he was shot. Hasan was paralyzed for the chest down.
The final witness called by the prosecution, Dr. Tonya Kozminski, testified about what Hasan told her would happen to the Army if he were deployed.
"The last thing he said ... 'They will pay," Kozminski said.
2. Admission of guilt
There is no question about whether Hasan carried out the shooting rampage, as he took credit for it at the outset of the trial, telling the military jury of 13 officers during opening statements that the evidence will show "I was the shooter."
The judge, Col. Tara Osborn, has refused to allow Hasan to argue "defense of others," a claim that he carried out the shootings to protect the Afghan Taliban and its leaders from U.S. soldiers.
The judge barred Hasan from pleading guilty at the start of the court-martial. Under military law, defendants cannot enter guilty pleas in capital punishment cases.
But in recent weeks, he has leaked documents through his civilian attorney to The New York Times and Fox News that appear to offer a glimpse of Hasan's purported justification for carrying out the attack. Among the documents was a mental health evaluation conducted by a 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.
3. Hasan's defense
Witness after witness pointed to the wheelchair-bound Hasan, identifying him as the gunman.
Throughout most of the testimony, Hasan has sat impassively and declined to question or challenge witness statements.
Much has been made of Hasan's defense or, as his stand-by attorneys have said, the lack of it. The judge declined a request by Hasan's attorneys to drop out of the case. The attorneys argued that Hasan was helping the prosecution put him to death.
There may be something to that claim.
In the mental health evaluation that Hasan released to The Times, he told the military panel: "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."
4. Will he testify?
Hasan previously indicated that he intended to call himself and two witnesses to the stand. If he testifies, Hasan is expected to discuss religious justification for his actions.
But there is a question of whether Hasan will even put on a defense after he told the court he no longer wished to call to call his witnesses -- Dr. Lewis Rambo, an expert on religious conversion, and Dr. Tim Jon Semmerling, who specializes in mitigating factors in criminal cases.
That leaves just Hasan, and the question of whether he will testify or wait until closing statements to speak.
"If you choose to testify, it is your choice and your choice solely," the judge told Hasan.
"If you do testify, you have to ask yourself questions. ... You can't simply give a statement. It has to be in a question-and-answer format."
5. What's next?
Once Hasan rests his case, which could come as early as Wednesday morning, and both sides complete their closing statements, the case will be handed to the jury.
If the jury finds Hasan guilty, the judge will then convene the sentencing phase of the court-martial -- essentially a mini-trial -- where a jury will determine