Fort Hood, Texas (CNN) -- The Army psychiatrist accused of last year's deadly shootings at Fort Hood faced the most severely injured victim Thursday in a small military courtroom.
Maj. Nidal Hasan looked down as Staff Sgt. Patrick Zeigler described his four bullet wounds, and how part of his brain had to be removed because of skull and bullet fragments.
Zeigler, using a cane, walked slowly to the witness stand, for the last testimony of the day in a military hearing that is expected to last for weeks.
He told how he heard the gunman shout out "Allahu Akbar" just before the firing began.
"After I heard that I pretty much froze up because I knew what that meant," said Zeigler, referring to the Arabic phrase meaning "God is great."
Other witnesses have identified Hasan as the gunman who shouted out in a crowd of soldiers and opened fire. The Army colonel overseeing the Article 32 hearing will decide if there is sufficient evidence to proceed to a court martial, with a possible penalty of death.
Hasan is accused of killing 13 people and wounding 32 others, including Zeigler.
Moments before he was shot the first time, Zeigler said he saw the red laser mounted on the handgun cross his vision.
"It felt like somebody hit me in the side of the head with a metal baseball bat," Zeigler said about the impact of the bullet.
Zeigler had just come back from his second deployment to Iraq and was bound for officers candidate school. His injuries on November 5, 2009, were so severe he was not expected to survive, and in the aftermath of the shootings he was sometimes referred to as the 14th fatality.
Thursday, he made his way haltingly to the witness stand, with a cane in one hand. His fiance, Jessica Hansen, was in the courtroom as she has been at his side for 10 months of hospitalization, multiple operations and almost daily physical therapy.
"I basically knew I was in serious trouble," Zeigler said about the seconds following his shooting. "There was a pool of my own blood in front of me."
Zeigler was shot four times, in the right side of his head, left shoulder, left forearm and left hip. More than 18 percent of his brain was removed, he said. And he has fought back from partial paralysis.
Hasan himself remains partially paralyzed and was wheeled into the courtroom in a wheelchair. He, too, was shot four times by police who rushed to the scene.
After Zeigler's testimony, people in the courtroom and journalists watching a video feed from a remote press room could hear the steady tap-tap of his cane as he slowly made his way out. His fiance, who has said she will attend ever day of the hearing, rose and touched him on the arm as he walked past.
Earlier Thursday, a parade of soldiers pointed at Hasan and identified him as the gunman in the shootings.
Hasan sat in the courtroom in his wheelchair, wearing a cap and covered by a blanket.
"Yes sir, that's him," said Staff Sgt. Paul Martin after Hasan removed his cap.
Martin was wounded in his left arm.
"I've never been hit by something that hard in my life and it hurt," Martin said.
Spc. Grant Moxon said he also heard a shout and then gunshots. "I just heard a yell and shots directly following. It seemed the individual was pulling the trigger as fast as he could," Moxon said.
He told a military hearing that he still carries a bullet in his leg.
By mid-afternoon Thursday, the prosecution had called 16 of what are expected to be dozens of witnesses, building layer upon layer of details of what happened in the few moments that the shooting lasted.
The defense seemed to have a pattern of asking each prosecution witness to describe how they were treated for their physical injuries and whether they are continuing to receive mental health treatment or counseling.
Spc. Alan Carroll testified that he thought he was thrust into the middle of a training exercise, but the soldier said he soon realized that a man was shooting real bullets at a processing center at Fort Hood last year.
Carroll was shot four times. He's now serving in Afghanistan, and he spoke Thursday via video-link on the third day of the military hearing about the shootings.
"At first I thought it was some kind of training simulator," he said.
"It was continuous. It was non-stop -- pop pop pop pop," Carroll said about the gunshots on November 5, 2009. Despite his injuries, Carroll was judged fit to return to active duty in December.
He said "battle buddies" and others had suggested he seek further counseling in the aftermath of the incident but he had refused.
"It is just bringing up that day and I just want to forget about it," Carroll said.
Carroll said in thick of the shooting he tried to fulfill his Army duty never to leave behind a fallen comrade. But his injuries made that impossible.
"They all three died, passed away," Carroll testified about his friends.
Spc. Keara Bono was reading a book in the Fort Hood building where the shootings occurred, moving through the paperwork and medical tests to deploy to Iraq. Suddenly she was wounded in the head.
"At that moment all I smelled was blood because my face was covered with it," she testified.
Spc Jonathn Pagel said he suddenly felt a burning in his chest. "I put my hand up there and realized I was bleeding," he said.
It was hard to track how long the shootings lasted -- "it seems like an eternity," he said.
And he said the shots kept coming. " It was pretty rapid, to me it sounded almost like a fully auto."
Another witness, 1st Lt. Brandy Mason, told how she also thought at first the firing was part of a training exercise.
"He fired off his first clip and someone hollered out, 'Training or not, get down, get down,'" Mason said.
Asked to identify the gunman, she pointed at Hasan, sitting in his wheelchair.
Mason said she didn't realize she had been shot in the thigh until she was getting medical help.
Thursday was only the second day of full testimony in the hearing. The hearing's investigating officer, Col. James Pohl, will hear all the evidence before ruling whether the case will move to a court martial. Defense attorneys have said they expect prosecutors to seek the death penalty for Hasan.