Toronto-born Omar Khadr, the youngest detainee ever held at the US \"war on terror\" prison at Guantanamo Bay, Cuba, has officially asked to return home to Canada, one of his lawyers said Tuesday. \"He is still in Guantanamo,\" attorney John Norris told AFP. \"But we have submitted an application (for his repatriation to Canada) and we understand that the process is underway.\" A US military tribunal sentenced Khadr to 40 years in prison in October 2010 after he pleaded guilty to throwing a grenade that killed a US sergeant in Afghanistan in 2002. He was only 15 at the time. But a plea deal meant his actual sentence was only eight years -- including a provision that he could seek a transfer to Canada after an initial year at Guantanamo. That year ended on Monday. \"We\'ve reached that milestone,\" said Norris. Washington must first give its approval for the transfer, and then Ottawa would consider the request. Both gave tacit approval as part of the plea deal, but did not commit themselves to when they would make that decision. \"We\'re hopeful that will happen very soon,\" Norris said. Canadian legal scholars suggested Ottawa might seek assurances from Khadr that he will not launch any further legal challenges in a bid to seek earlier release, before agreeing to his transfer to a Canadian prison. Mike Patton, spokesman for Public Safety Minister Vic Toews, said the case would be reviewed \"solely on its merits,\" like any other international prisoner transfer. \"I\'m not aware of any objections\" to Khadr\'s repatriation, he added, but noted that a decision could take up to 18 months. \"We don\'t have any inside information, but nobody has identified any obstacles to us,\" said Norris. \"The bureaucracy may need some time to move. We\'re hopeful it will move quickly in this case.\" Khadr hired Norris and Brydie Bethell to represent him after firing Canadian civil rights lawyers Dennis Edney and Nathan Whitling in August, signaling a possible change in legal strategy. Edney and Whitling had worked on Khadr\'s case pro bono for nearly eight years, even paying for their own transportation to Guantanamo. It was on their advice that he agreed to plead guilty to the charges in order to leave Guantanamo sooner. Born in Toronto in 1986 to a family of militants, Khadr was a beardless teenager when he was captured while severely wounded in Afghanistan. Today, at 25, he is a tall man with a heavy beard and a scarred face. The Khadr family went to Pakistan when Omar was a child to help with reconstruction along the Pakistan-Afghan border following the withdrawal of Russian troops, according to an online family biography. Khadr returned to Canada in 1995, going back to Pakistan the following year. His family then lived in a compound in Jalalabad, Afghanistan, where he allegedly met Osama bin Laden.