A US Army sergeant who was held captive by the Taliban before being freed in a prisoner swap has said he was tortured during his five years of detention.
Bowe Bergdahl said he was beaten with a copper cable as he spent months blindfolded and chained spread-eagle to a bed.
The 28-year-old soldier described his harsh treatment in Afghanistan in a letter that has been released by his defence lawyer.
The Army charged Sgt Bergdahl with desertion and misbehaviour before the enemy for leaving his post in June 2009. He faces up to life in prison if convicted of the criminal charges.
Sgt Bergdahl was freed last year in exchange for five Taliban commanders held prisoner at Guantanamo Bay, Cuba.
In the letter, he says he suffered from hunger, thirst and serious infections from sores that developed where his hands and feet were bound to the bed.
The case against Bergdahl, 28, has been highly politicised, with members of Congress demanding he be sent to prison. The charges prompted fresh criticism of President Barack Obama.
Sgt Bergdahl says he tried about a dozen times to escape and his captors' response was brutal.
"In the beginning of my captivity, after my first two escape attempts, for about three months I was chained to a bed spread-eagle and blindfolded," he wrote.
"Around my ankles where the chains were, I developed open wounds ... During these months some of the things they did was beat the bottoms of my feet and parts of my body with a copper cable."
He also says he was beaten with a rubber hose, fists and hit with the butt of an AK-47, so hard the rifle's stock broke off.
He says he was repeatedly threatened with execution and "kept in constant isolation during the entire five years", much of the time in a small cage in dark rooms, chained to a heavy object.
When he was finally set free, he could hardly walk.
Eugene Fidell, one of Sgt Bergdahl's lawyers, said this suffering should be considered when weighing any punishment.
He next faces a hearing where a high-ranking officer known as the "convening authority" will decide if there is enough evidence to recommend the case to a court martial.
"This is a hellish environment he was kept in for nearly five years, particularly after he did his duty in trying to escape," Mr Fidell, a former military lawyer now in private practice, said.
"There is no question in my mind that a convening authority would not be doing his or her duty without taking into account the circumstances under which Sgt Berhdahl was held."
Sgt Bergdahl's two-page description of his captivity was attached to a letter Mr Fidell sent on March 2 to General Mark Milley, who runs the US Army Forces Command at Fort Bragg and was responsible for deciding any criminal charges.
He was captured by the Taliban shortly after leaving his post and held by members of the Haqqani network, an insurgent group tied to the Taliban that operates both in Pakistan and Afghanistan.
Before disappearing, Sgt Bergdahl had expressed misgivings about the US role in the war as well as his own.
Mr Fidell cited an Army investigation that determined he left his post but not the Army, and that his "specific intent was to bring what he thought were disturbing circumstances to the attention of the nearest general officer".
Mr Fidell argued that given his harsh captivity, the reason he left his unit and his attempts to escape while prisoner, "it would be unduly harsh to impose on him the lifetime stigma of a court-martial conviction or an Other Than Honorable discharge and to deny him veteran's benefits".
That argument apparently fell flat: The desertion charge carries up to five years in prison, while "misbehaviour before the enemy" carries a life sentence. A conviction on either could strip him of his rank and pay and earn him a dishonorable discharge.
The misbehaviour charge is rare and typically reserved for shameful or cowardly conduct, said Daniel Conway, a military defence lawyer and the author of a forthcoming book on military crimes.
But even some members of Sgt Bergdahl's former Army unit have called for serious punishment, saying others risked their lives searching for him, although the Pentagon says there is no evidence anyone died because of his actions.
The Obama administration is standing by the prisoner swap.
"Was it worth it? Absolutely. We have a commitment to our men and women serving overseas, or in our military, defending our national security every day, that we will do everything we can to bring them home, and that's what we did in this case," State Department spokeswoman Jen Psaki told Fox News.
Sgt Bergdahl still needs "continuous physical therapy, medical and behavioural health appointments" at the Army medical centre at Fort Sam Houston in Texas, where he has been assigned to a desk job.
Even in Texas, he faces "hostility" that raises doubts about a fair trial, Mr Fidell wrote. Two officers accompany him wherever he goes off base, not to keep him from escaping but to protect him from others.