Video report by ITV News' Paul Davies
The British man identified as the Islamic State executioner known as "Jihadi John" was a "popular" schoolboy who loved Manchester United and pop band S Club 7.
Mohammed Emwazi, 27, is understood to be the masked militant who has appeared in numerous videos showing the brutal murders of Western hostages.
Writing in a school yearbook when he was 10, Emnazi said his favourite computer game was 'Duke Nuke: Time to Kill' and best book was 'How to Kill a Monster'.
Emwazi, who was born in Kuwait before moving to London and joining St Mary Magdalene Church of England primary school in Maida Vale when was six, also states his ambition to become a professional footballer.
Asked where he wants to be by the time he is 30, Emwazi - who says his nickname is "Mo" - writes: "'I will be in a football team and scoring a goal."
He also lists his favourite food as chips, his favourite animal as a monkey, his favourite colour as blue and his favourite cartoon as The Simpsons.
One former classmate told the Daily Mail that Emwazi was "popular" and one of the "sporty guys".
"He played football every lunchtime and at the after-school football club. Through football, he learned different words and expressions. Like all the guys, he always wanted to be the striker."
Another said he was "completely shocked" by news Emwazi was believed to be the Islamic State murderer.
"He seemed like a normal kid," the ex-classmate told The Sun.