saying you're doing this this this, we're keeping a close eye on you. you already have been. we're going to keep a close eye on you. >> reporter: slowly we are getting a closer picture of who emwazi was before he became the masked murderer he was today. the former head master of emwazi's high school remembers him fully. >> was bullied a bit because he was quiet and reserved. but generally he was final. there was no issues with him, no massive behavior problems with him. and by the time he got into the -- he had settled and worked hard. achieved great grades. >> reporter: when did you first hear that mohammed emwazi was in these horrific videos? >> my blood ran cold. even now when i hear the name i find it incredible that to marry what is seen on the tv with the person i knew it literally makes the hairs on the back of my head stand up. >> reporter: for the people who knew him, it's difficult to