The inquiry would also focus on whether Germany served as a silent partner of the United States in the abduction of Khaled el-Masri , a German citizen of Arab descent who was taken to an American prison in Kabul , Afghanistan , where he said he was held and tortured for five months after being mistaken for a terrorism suspect , and on the purpose of hundreds of C.I.A . flights between 2001 and 2005 that crossed German airspace .