A military officer testified Monday that he saw another soldier shot in the head during the 2009 search for U.S. Army Sgt. Bowe Bergdahl, who's accused of endangering his comrades when he walked off his post in Afghanistan.

The testimony came at a pretrial hearing at which an Army judge also agreed to delay Bergdahl's trial by several months until May 15, 2017.

Prosecutors are arguing that the judge should allow evidence of two wounded soldiers' injuries into the case to help them show that Bergdahl's disappearance effectively put other military members in harm's way.

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Bergdahl is charged with desertion and misbehavior before the enemy, the latter of which carries a maximum penalty of life in prison.

U.S. Air Force Maj. John Marx testified about a firefight on July 8, 2009, when he and several other U.S. military members were seeking information on Bergdahl's whereabouts, with members of the Afghan National Army. They were attacked after setting up a checkpoint near a town in Afghanistan.

One of the two wounded soldiers cited by prosecutors is U.S. Army National Guard Sgt. First Class Mark Allen. Prosecutors said he was shot in the head and suffered a traumatic brain injury that has left him in a wheel chair. Another soldier had hand injuries and required surgery because of a rocket-propelled grenade.

Marx, who said the mission's sole purpose was to search for Bergdahl, testified that he was sitting next to Allen as bullets flew overhead.

"I looked at him, then I see a trickle of blood coming down his head," Marx testified. Asked where Allen was wounded, Marx pointed at his temples and said: "Right through his head."

Marx testified that he later carried Allen to the medevac helicopter, describing it as "probably one of the toughest things I've ever done in my life."

Bergdahl, dressed in a white shirt and blue pants, appeared stoic as he listened to Monday's testimony.

Prosecutors have written in a motion that the injuries will help them show that Bergdahl endangered his comrades, one of the elements of the misbehavior before the enemy charge. They asked the judge to allow them to use the evidence in their case.

Defense attorneys have argued in motions that Bergdahl was not responsible for the men's injuries, writing: "Allen's injuries were directly caused by the Taliban, not by SGT Bergdahl."

Further testimony and arguments are expected Monday afternoon.

Before the testimony on the soldiers' injuries, Army Col. Jeffery Nance decided to push the trial back to May after prosecutors requested a delay. They cited the pace at which they're able to get approval to give the defense classified evidence.

Defense attorneys also informed the judge that they were still waiting on software, computers and security equipment that would allow them to review some of the sensitive material.

Nance expressed frustration and told prosecutors that he would call military officials as witnesses at a pretrial hearing in December if some of the issues with classified information aren't resolved.

"Here's my problem folks ... We will nickel and dime this until we're not trying this case until 2020," he said.

Bergdahl, who's from Hailey, Idaho, walked off his post in Afghanistan in 2009 and was held captive by the Taliban and its allies for five years. The Obama administration's decision to swap prisoners for his return was heavily criticized by some Republicans.