Updated

A military judge expressed skepticism Monday that letters destroyed by a top general are relevant to the prosecution of Bowe Bergdahl on charges related to his leaving his post in Afghanistan.

The judge, Army Col. Jeffery Nance, is likely to decide later in the afternoon whether the general who leads U.S. Forces Command will testify this week during pretrial hearings this week at Fort Bragg.

Bergdahl's attorneys argue that Gen. Robert B. Abrams faced improper conflicts when he referred Bergdahl for a general court-martial rather than a lower-level prosecution. Abrams has acknowledged destroying around 100 letters that were largely sent by the general public regarding the Bergdahl case. He sent them to an incinerator in a "burn bag."

The destruction of the letters is one of several reasons why the defense says Abrams should be disqualified from the case. They also cite his prior role advising former U.S. Defense Secretary Chuck Hagel during efforts to return Bergdahl from captivity as well as questions about whether he considered defense objections to the findings of a preliminary hearing. The defense is seeking a reset in the case that would allow another commander to decide whether it warrants a general court-martial.

Prosecutors say the letters didn't constitute evidence and that Abrams shouldn't be required to testify, nor should he be disqualified.

Nance said it was "unrealistic" to expect that Abrams would have been insulated from all public comment about the case.

"I'm having a hard time seeing any relevance," he said, referring to the letters that were destroyed.

But Nance also said there were unanswered questions that testimony by Abrams could clarify.

Defense attorney Eugene Fidell argued that the letters were valuable for a number of reasons, saying they were "the kinds of things that could lead to investigative leads" for Bergdahl's lawyers as they prepare his defense.

Bergdahl, who is from Hailey, Idaho, walked off his post in Afghanistan in 2009 and wound up as a captive of the Taliban and its allies until 2014. The Obama administration won his release by swapping him for Guantanamo Bay detainees. Bergdahl faces a court-martial on charges of desertion and misbehavior before the enemy. The latter charge carries up to a life sentence.

Defense attorneys argue in a separate motion that public comments by U.S. Sen. John McCain impermissibly tainted the case. Legal experts have described the defense motions as longshots, and prosecutors have said in legal filings that it would be "unprecedented" for the judge to dismiss charges against Bergdahl based on the arguments about McCain.

Bergdahl's military trial is scheduled for February 2017.