Left his post: Army Sgt. Bowe Bergdahl walked away from the army and was captured by the Taliban in June of 2009 . The former Chairman of the Joint Chiefs Admiral Mike Mullen knew that Army Sgt. Bowe Bergdhal deserted his post in 2009, claim three of the controversial soldier's comrades. The men say that Mullen, who served President Obama and then Secretary of Defense Robert Gates six years ago, was certain that Bergdahl had fled the army and was guilty of desertion. The claims mean that Mullen was in a position to tell the president his soldier had run away five years before National Security Adviser Susan Rice told the world that Bergdahl served honorably. It also casts a huge shadow over the deal to swap five Taliban commanders for Bergdahl that culminated in a Rose Garden ceremony hosted by Obama to celebrate his release and attended by his parents. 'I asked him (Mullen) if he knew about Bergdahl and that he deserted and he (Mullen) told me that he knew of the circumstances surrounding his walking off,' said former Sgt. Matt Vierkant told Fox, 'and that they were developing leads and following leads, trying to do everything they could to get him back.' This development comes one week after officials scheduled a July hearing for the Army sergeant who left his post in Afghanistan and was held by the Taliban for five years. Bergdahl says he walked away because of PTSD and is not a deserter. Vierkrant claims he and two other collegagues, Evan Buetow and Cody Full, were providing security for Mullen while he was on a trip to Afghanistan in December 2009 - six months after Bergdahl was captured. Vierkrant claims that during an unguarded question and answer session, Mullen said they could ask him anything. 'So Matt asked him, you know Bergdahl deserted, what's going on with that? And Admiral Mullen said, 'Yes, we know all the circumstances surrounding Bergdahl walking away from the OP (outpost,)and we're still working on getting him back, figuring out where he is and kind of figuring out that whole situation.' Scroll Down for Video . Admiral Mike Mullen, former Chairman of the Joint Chiefs of Staff, allegedly told three comrades of Bergdahl that the soldier was a deserter . Specialist Cody Full confirmed that this is what Mullen said as did Buetow. 'I don't remember him being taken aback by it at all, you know, he knew what was going on, he answered not confidently but he didn't have to think about it, he didn't want to give us some political answer,' Buetow explained to Fox. 'He just gave us an answer.' According to former White House aides this means it is inconceivable that Mullen would not have told President Obama and raises questions as to the prisoner swap for a known deserter. 'If Mullen knew, and now it's alleged that he did know, it would be, it would be unthinkable that he didn't pump this up the chain of command, his chain of command, or, tell the president directly,' said Brad Blakeman, a former Bush White House staffer to Fox News. 'At a minimum, this would have been included in the president's daily brief, and at a maximum, it would've been told directly to the President by Mullen.' Days after his rescue (right), Bergdahl (pictured left in a video released by the Taliban in 2010) was in stable condition at a U.S. military hospital in Germany . U.S. President Barack Obama stands with Bob Bergdahl (R) and Jami Bergdahl (L) as he delivers a statement about the release of their son, prisoner of war U.S. Army Sergeant Bowe Bergdahl, in the Rose Garden at the White House in  May, 2014 . Mullen spoke to Fox News and defended his decisions. 'From the moment Sgt. Bergdahl went missing, the U.S. Military was focused on finding him--as it does with any serviceman or woman who goes missing. The exact circumstances were not known then, nor did they drive our decisions. We do not leave our people behind.' Vierkant said that he wants to know what his superior officers knew and when they knew it. 'I want to ask him (Mullen) did they brief the White House? Who knew about it and why would you still do this trade knowing all the information that you knew?' said Vierkant. 'We don't leave anyone behind. The thing is, we never left him (Bergdahl) behind. He left us behind. He chose to walk off and do whatever and get captured, that was his fault. Those were his choices.' Bergdahl is charged with desertion and misbehavior before the enemy. Army officials announced Thursday that his Article 32 hearing will be held July 8 at Fort Sam Houston, Texas. That proceeding is similar to a civilian grand jury. From there, it could be referred to a court-martial and go to trial. Officials say Bergdahl walked away from his post in Afghanistan and was captured by the Taliban. He was then released from Taliban control in a prisoner exchange last May for five Taliban commanders. He faces up to life in prison if convicted of misbehavior before the enemy.
Former Sgt. Matt Vierkant claims Admiral Mike Mullen knew Bergdhal deserted . Claims the Chairman of the Joint Chiefs told him this during private question and answer session . Ex-White House aides have said it is inconceivable that President Obama did not know . Bergdahl is charged with desertion and misbehavior before the enemy .