Bowe Bergdahl Was 'Gold Mine' Of Information, Agents Say

Two military agents have given evidence that US Army Sergeant Bowe Bergdahl helped them understand insurgents better and provided a "gold mine" of information after he was returned in a prisoner swap.

The agents were called by the defence to bear witness on Tuesday at Bergdahl's sentencing hearing.

They said the information that he gave them will help train troops on how to survive future imprisonments.

The Army Sergeant pleaded guilty to desertion and misbehaviour before the enemy for walking off his post in Afghanistan in 2009 and now faces life prison.

"I understand that leaving was against the law," Bergdahl said.

"At the time, I had no intention of causing search and recovery operations," Bergdahl added, saying that now he does understand that his decision to walk off his remote post in Afghanistan in 2009 prompted efforts to find him.

Prosecutors have sought to show a military judge the severe wounds that troops suffered while searching for Bergdahl.

The 31-year-old could face up to five years in prison on the desertion charge and a life sentence for misbehaviour.

Bowe Bergdahl disappeared from his base in Afghanistan and was held in captivity by the Taliban for five years.

The circumstances of his capture remain unclear, with speculation that he might have abandoned his base out of disillusionment with the US military.

He was then liberated as a result of secret talks between the US government and the Taliban, who swapped him for five Guantanamo Bay prisoners.

However, in 2015 he was charged with desertion and endangering fellow soldiers.

He isn't only considered America's most notorious prisoner of war, but also the only US soldier held by the enemy in the Afghan conflict.