Fort Sam Houston, TX (CBS) --- Sgt. Bowe Bergdahl was in "good spirits" after the U.S. Army began questioning him about his disappearance in Afghanistan that led to five years in captivity by the Taliban, his lawyer told CBS News Wednesday.
Bergdahl was questioned at Fort Sam Houston in Texas where he has been staying since returning to the U.S., said his attorney, Eugene R. Fidell.
"He's in good spirits. Today was a long day but it wasn't a particularly stressful day," Fidell said. "It was ... I don't mean to say therapeutic but healthy in a kind of way and that's a good thing."
Maj. Gen. Kenneth R. Dahl, who is heading the probe into the 28-year-old's disappearance, questioned Bergdahl on Wednesday, Fidell said.
"General Dahl set a very informal tone, it was non-adversarial," Fidell said. "It was not mostly questions and answers. It was simply affording Sergeant Bergdahl an opportunity to tell his story in his own words."
A well-known lawyer and military justice expert who is currently a visiting lecturer at Yale Law School, Fidell described the setting of Bergdahl's interview as "a comfortable environment," a room with a sofa and a couple of chairs. He said there were four people in the room, the interview was being recorded and that they were taking breaks throughout the day.
It was not immediately known how long the interview would last. But Fidell said he expected this would be the only interview Bergdahl would be giving as part of the investigation.
Lt. Col. Alayne Conway, an Army spokeswoman, said Bergdahl was advised of his rights under Article 31 of the Uniform Code of Military Justice. Article 31 pertains to individuals being informed of the nature of the accusation against them and says that they do not have to make any statement to investigators.
"This in an ongoing investigation; the investigating officer has 60 days from his appointment to conclude his investigation; however, he can request additional time if he feels it is necessary," Conway said in an emailed statement. She did not respond to an inquiry about what type of questions investigators asked.
Fidell told CBS News that Bergdahl has been encouraged by the many messages of support that the lawyer has received on his behalf.
"It has been very helpful to him for a guy who's been in quite a lonely and terrible experience for a long time," Fidell said.
The Idaho native was freed by the Taliban May 31 in a deal struck by the Obama administration in which five senior Taliban officials were released from detention at Guantanamo Bay, Cuba. Bergdahl had disappeared from his post in Paktika province in eastern Afghanistan on June 30, 2009. Some ex-members of Bergdahl's former unit have labeled him a deserter, asserting that he chose to walk away and saying some were wounded or killed looking for him.
In July, a bitterly divided House panel voted to condemn Obama for the swap for Bergdahl.
The investigation's findings will help determine whether Bergdahl is prosecuted for desertion or faces any other disciplinary action.
Bergdahl had been receiving care at Fort Sam Houston since returning to the United States on June 13. He was treated at Brooke Army Medical Center at the fort but was later shifted to outpatient care at the military base.
Earlier this month, the Army announced Bergdahl had been given a desk job, ending the formal phase of his transition from Taliban prisoner to not-quite-ordinary soldier.
Bergdahl has not commented publicly on the circumstances of his disappearance, and the Army has made no charges against him.
It is unknown if Bergdahl's family has seen him since his return to the United States. Army officials have said because of a request by Bergdahl's family for privacy, they cannot comment on that matter.
"Even Sergeant Bergdahl is entitled to a private life," Fidell said. "I think he's looking forward to really becoming just another face in the crowd and not so much in the news."