Mohammed Emwazi, named by media and experts as the militant who allegedly beheaded at least five Western hostages held by the Islamic State group, told the Mail on Sunday reporter that he felt like a "dead man walking".
A British civil rights group that was in contact with Emwazi claims that domestic spy agency MI5 had been tracking him since at least 2009, and blamed his radicalization on their "harassment".
Emwazi was born in Kuwait but moved to London as a child and attended school and university in the British capital.
It was also reported that Emwazi had contacts with the men responsible for failed attacks on London's public transport system in 2005, two weeks after suicide bombings killed 52 people in the capital.
The revelations add to pressure on the security and intelligence agencies to explain why they did not act on their suspicions about Emwazi before he travelled to Syria.
