U.S. soldier Bowe Bergdahl, whose return this week from Taliban captivity fuelled controversy after five militants were released from Guanatanamo Bay in exchange, apparently wandered away from his military base on several previous occasions both at a training range in California and at his remote outpost in Afghanistan – and then returned, according to a leaked, classified military report.

Attributed to “people briefed” on the report the New York Times said that Sergeant Bergdahl, “most likely walked away of his own free will from his outpost in the dark of night… for a short adventure amid an environment of lax security and discipline,” and then ended up getting captured by hostile forces.

The prisoner swap came under fire, including from Republicans on Capitol Hill, after accounts by Sgt. Bergdahl’s former colleagues suggested that he may have been a deserter or even enemy collaborator, and the soldier’s father was noted to have been sending supportive messages to a Taliban spokesperson on Twitter.

Although the Pentagon declined to comment on the leaked classified report the NYT pointed out that the investigation into Sgt. Bergdahl’s conduct concluded that “He may have taken a shorter unauthorised walk outside the concertina wire of his combat outpost in eastern Afghanistan before he left for good, in an episode that was apparently not reported up the chain of command.”

The internal Pentagon report was apparently authored in July and August of 2009 based on extensive interviews with members of Sgt. Bergdahl’s unit, including his squad leader, platoon leader, and company and battalion commanders.

Although some senior lawmakers including Senator Dianne Feinstein of the Select Committee on Intelligence said that a White House official had called to apologise for not giving Congress the mandatory 30-day notice before undertaking the prisoner swap, the administration hit back at criticism on Thursday and the President said he made “absolutely no apologies” for the way Sgt. Bowe Bergdahl was returned from Afghanistan.

More In: World | International | News