Sometime after midnight on June 30, 2009, Pfc. Bowe Bergdahl left behind a note in his tent saying he had become disillusioned with the Army, did not support the American mission in Afghanistan and was leaving to start a new life. He slipped off the remote military outpost in Paktika Province on the border with Pakistan and took with him a soft backpack, water, knives, a notebook and writing materials, but left behind his body armor and weapons — startling, given the hostile environment around his outpost.

That account, provided by a former senior military officer briefed on the investigation into the private’s disappearance, is part of a more complicated picture emerging of the capture of a soldier whose five years as a Taliban prisoner influenced high-level diplomatic negotiations, brought in foreign governments, and ended with him whisked away on a helicopter by American commandos…

“Yes, I’m angry,” Joshua Cornelison, a former medic in Sergeant Bergdahl’s platoon, said in an interview on Monday arranged by Republican strategists. “Everything that we did in those days was to advance the search for Bergdahl. If we were doing some mission and there was a reliable report that Bergdahl was somewhere, our orders were that we were to quit that mission and follow that report.”