— -- Capt. John Billings, the platoon leader who was Bowe Bergdahl's commanding officer before Bergdahl left his post in Afghanistan, testified today, saying how soldiers spent weeks searching for him.
The testimony comes as Bergdahl faces a hearing to determine whether he should face a military tribunal over his charges of desertion over the 2009 incident, which military officials said led to his being captured by the Taliban. Bergdahl has been charged with desertion and misbehavior before the enemy. Should the case be referred to a court martial he could face a maximum penalty of life in prison.
Maj. Margaret Kurz, who was leading the prosecution, said that Bergdahl showed deliberate disregard for his unit by leaving his post.
"He was intending to draw attention to himself," she said during the hearing today at Fort Sam Houston in San Antonio, Texas.
"Under the cover of darkness, he snuck off the post,” Kurz said.
Bergdahl, who was returned to the U.S. as part of a prisoner exchange with the Taliban in 2014, was present in court but said little.
He looked down for much of the first portion of the hearing, responding "Yes, sir" when he was asked a question during his defense's opening statement. Bergdahl was dressed in his Army service uniform with his hair in a crew cut.
His attorney, Eugene Fidell, has cited an investigation that concluded that Bergdahl did leave his post but not the Army generally, according to the Associated Press, and that his "specific intent was to bring what he thought were disturbing circumstances to the attention of the nearest general officer."
Fidell said he will be calling witnesses, but has not specified as to whether Bergdahl will be speaking, the AP reported.
The first witness who was called after both sides made their opening statements was Capt. John Billings, Bergdahl's platoon leader. He said that his first impression of Bergdahl was that he was a great soldier.
He then described how intense the searches were for Bergdahl, and how they increased from one per day to several each day.
"I was exhausted mentally and physically," Billings said.
Billings told his soldiers they must "exhaust all means and do everything we have to do to find Bergdahl."
"This is absolutely the most important thing they will ever have to do in their life," Billings said. "I was defeated. For the first time in my career I had lost a soldier."
"I felt almost as if I had failed my men," he added.
The prosecution indicated the disappearance was premeditated, noting that Bergdahl had emailed his girlfriend, saying "be prepared and expect something."
Major Silvino Silvino, Bergdahl's company commander, was called as a prosecution witness and said that he had to "take tactical risks" to search for Bergdahl, noting that 80 percent of their vehicles were damaged by IEDs or sheer wear and tear from the search. All four of their mine rollers were destroyed and they had to take from other companies, he said.
The hearing is ongoing.
ABC News' Luis Martinez contributed to this report.