The federal prosecutor's office said today that Muhammad Aafaq I, whose last name was not given in accordance with privacy regulations, joined the group in 2008 to fight in Kashmir.
Prosecutors say he trained with the group in Pakistan, learning to use weapons like assault rifles and rocket launchers before becoming a trainer of new recruits.
They say he fled the group in 2011 after reports that it was supported by Pakistani intelligence and was fighting with the Taliban in Afghanistan, "contradictory to his motivation." They didn't say how he got to Germany.