The oldest detainee at Guantanamo Bay — an Afghan man who is at least 71 and hobbled around the U.S. prison in Cuba using a walker — has been sent home, his lawyer said Monday. Haji Nasrat Khan was among five men from Afghanistan transferred over the weekend, said attorney Peter Ryan, who received the news in an e-mail from the U.S. Department of Justice.

Ryan was not told why Khan was transferred, and was trying to determine whether he would be held in custody in Afghanistan or allowed to return home. The U.S. military did not disclose the names of the five men sent back to Afghanistan and declined to comment.

Khan was not charged with a crime and Ryan said the government never said why he was detained. "We couldn't figure out why he was there," Ryan said. "He could barely walk and he could barely hear." Khan told his lawyers he believes he's around 78, but doesn't know his exact age. He is at least 71, according to military records obtained by The Associated Press.

With the latest transfers, the military now holds about 445 men on suspicion of links to al-Qaida or the Taliban, including about 115 who the U.S. has determined are eligible for release or transfer.