Until recently, Mohammed Emwazi was known as 'Jihadi John', the ISIS militant with a knife and a British accent in the propaganda videos beheading Western hostages. A U.S. intelligence official confirmed with NBC News that the man is a 26-year-old Kuwaiti-born British citizen who left the United Kingdom and radicalized after numerous run-ins with intelligence officials. Emwazi was raised in West London after leaving Kuwait when he was 6 years old. He attended the University of Westminster until 2009. Emwazi told CAGE, a British human rights group that worked with him, that he wanted to use his degree for a successful career in Arab countries. According to CAGE, he become disillusioned when British security officials prevented him from traveling abroad, including a trip with friends to Tanzania and visit to Kuwait, where he had a job and fiancee. "I feel like a prisoner, only not in a cage, in London," Emwazi wrote to a police complaints commission in 2010. CAGE director Asim Qureshi said that he believed secutiry forces' treatment of Emwazi led him to radicalization. He became associated with several people in West London who later became involved with Somali terror group al Shabab, according to Duncan Gardham, a security expert and journalist in London.