SAN ANTONIO, TX (CNN) - A hearing into whether Army Sgt. Bowe Bergdahl should face a military court-martial is expected to resume Friday morning.
Prosecutors began presenting arguments Thursday on whether a court-martial should be initiated over Bergdahl's disappearance from a base in Afghanistan.
He vanished in June 2009 after deserting his unit, authorities said.
The incident set off a series of events that included his five-year capture by the Taliban. President Barack Obama later freed five members of the terror network held at Guantanamo Bay, Cuba, in exchange for Bergdahl last year.
As part of the controversial prisoner swap, Bergdahl returned to the United States. In March, the military charged him with desertion and misbehavior before the enemy.
The Army Article 32 preliminary hearing is happening at Joint Base San Antonio-Fort Sam Houston in Texas.
At Thursday's hearing, government prosecutors called witnesses who represented Bergdahl's chain of command.
His former platoon leader, Capt. John Paul Billings, recounted soldiers awakening him early to say Bergdahl was missing.
"I didn't really know what to say. I was in shock, in absolute disbelief that I couldn't find one of my own men. It's a hard thing to swallow," Billings said, adding that a squad immediately went out to look for him.
On cross-examination, Billings said Bergdahl appeared to be completely normal the day before he disappeared, that he had been dedicated to the mission, and had an outstanding record of performance.
The defense also asked the platoon leader if he had been made aware that Bergdahl had a psychological discharge from the U.S. Coast Guard, or that Bergdahl "possessed a severe mental disease or defect?"
Billings said he would have recommended Bergdahl to specialist care if he had known of any such mental issue.
During the hearing, Berghdahl sat at a long table with his civilian and military defense attorneys. He spent much of the proceedings looking down as he took notes on a pad in his lap.
5 Taliban detainees for Bergdahl
Some in the military and those who fought alongside Bergdahl in Afghanistan blasted the prisoner swap deal.
Obama has hailed Bergdahl's safe return to the United States.
"Sgt. Bergdahl has missed birthdays and holidays and the simple moments with family and friends," the President said when the soldier returned.
But Bergdahl faces the prospect of never spending another birthday or holiday outside of prison.
If his case goes to court-martial and he is found guilty of misbehavior before the enemy, he faces a potential maximum penalty of life in prison.
A court-martial would put the White House in a precarious situation. It has steadfastly defended the decision to recover Bergdahl amid backlash from Republicans and some who served with him in Afghanistan.
At the time of his recovery, U.S. officials said Obama's national security team was unanimous in its support of the prisoner exchange that ultimately returned Bergdahl to the United States.
Concerns about his physical health prompted them to circumvent a requirement to notify Congress about pending prisoner releases, authorities said at the time.
Obama cited a "sacred rule" in attempting to rescue American servicemen and -women, no matter the circumstances surrounding their capture.
"We still get an American soldier back if he's held in captivity. Period. Full stop. We don't condition that," he said at the time.
Some members of Bergdahl's unit have accused him of purposely abandoning his post before being captured in remote Afghanistan. Some suggested the U.S. effort to rescue him was misguided.
Allegations that he abandoned his post were well-known before his rescue became public, though they hadn't yet been subject to the type of Army investigation that followed his return.
The White House has expressed no regret at the decision to swap the Idaho native with Taliban prisoners.