For more than 90 minutes, the prosecutor took the jury methodically through the evidence in the case, meticulously piecing together how he said Hasan prepared and planned for the attack.
Prosecutors have maintained that the American-born Muslim underwent a progressive radicalization that led to the massacre at the sprawling central Texas base.
"He did not want to deploy, and he came to believe he had a jihad duty to kill as many soldiers as possible," Col. Steven Henricks told the jury.
Hasan picked the day -- November 5, 2009 -- because it was when the units he was scheduled to deploy with to Afghanistan were scheduled to go through the processing center, he said.
Hasan rested his case without calling a single witness or taking the stand to testify on his own behalf.
His decision not to offer a defense was an anticlimactic end to the trial in which prosecution witnesses, primarily survivors, painted a horrific picture of what unfolded inside a processing center during the attack.
During closing arguments, prosecutors showed a graphic FBI video of the crime scene hours after the rampage, where bodies, blood and bullets still covered the floor.
As the video was shown to the jury, some of the family members of those killed fought back tears.
One woman laid her head on her husband's shoulder, tears streaming down her cheeks, while another woman, a wife of a victim, left the courtroom.
For his part, Hasan watched the video, appearing to pay close attention
Much has been made of Hasan's defense or, as his stand-by attorneys have said, the lack of it. The judge, Osborn, 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.
Hasan took credit for the shooting rampage at the outset of the trial, telling the jury during opening statements that the evidence will show "I was the shooter."
Osborn barred Hasan from pleading guilty at the start of the court-martial. Under military law, defendants cannot enter guilty pleas in capital punishment cases.
The judge refused to allow Hasan to argue "defense of others," based on his claim that he carried out the shootings to protect the Afghan Taliban and its leaders from U.S. soldiers.
Perhaps as a way around that ruling, Hasan in recent days has leaked documents through his civilian attorney to The New York Times and Fox News that offer a glimpse of his 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'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," he told the panel, according to pages of the report published by The New York Times.
The judge excluded much of the evidence that the prosecution contends goes to the heart of the motive for the attack, including e-mail communications between Hasan and Anwar al-Awlaki, the U.S.-born cleric who officials say became a key member of al Qaeda in the Arabian Peninsula. He was killed in a U.S. drone strike in 2011.