Slahi worked at various companies in Mauritania as an electrical engineer starting in May 2000 . After the September 11 attacks , the U.S. renewed scrutiny of everyone suspected of having ties to al Qaeda . On September 29 , he was again detained by the Mauritanian authorities for questioning . He cooperated with the authorities several more times and then for the last time starting on November 20 , 2001 . Slahi was interrogated by both Mauritanian officials and the FBI for seven days
September 11 attacks
September 11 attacks
Mohamedou Ould Slahi