The British graduate unmasked as "Jihadi John" was bullied at school, his former headteacher has revealed.
Jo Shuter, the former headteacher of Quintin Kynaston, said she is horrified ex-pupil Mohamed Emwazi is the Islamic State fighter shown beheading Western hostages of the terror group.
She told BBC Radio 4's Today Programme: "I can't even begin to say the shock and the horror that I feel.
"Even now when I'm listening to the news and I hear his name I feel the skin on the back of my neck stand up because it is just so far from what I knew of him, and it is so shocking and so horrendous the things that he has done."
Ms Shuter said that far from the arrogant killer who features on IS videos, she remembered a "hard working" boy bullied by his schoolmates.
She said: "He had adolescent issues, as some of the young people, particularly at that age - year nine, particularly the boys, is a time when the hormones start raging, and he had some issues with being bullied which we dealt with.
"By the time he got into the sixth form he, to all intents and purposes, was a hard-working aspirational young man who went on to the university that he wanted to go to."
Emwazi moved from Kuwait to London when he was six. His family settled in the Mozart Estate - one of the capital's most notorious estates which has been blighted by gangs and violence.
Concerns have been raised that pupils at Quintin Kynaston - a flagship academy in Swiss Cottage, London, once visited by then prime minister Tony Blair - were radicalised as teenagers.
Choukri Ellekhlifi was killed in Syria in 2013 after joining up with an al Qaida terror group while Mohammed Sakr died fighting for al-Shabaab, an affiliate of al Qaida, in Somalia, according to reports.
But Ms Shuter said there was nothing to indicate the pupils were being radicalised and would go on to slaughter innocent people.
She said: "I am not prepared to say when the radicalisation took place. All I can say is absolutely hand on heart, we had no knowledge of it. If we had we would have done something about it."
She added: "There was never any sense that any of these young men as I knew them were radicalised when they were in school."
Ms Shuter said "categorically nobody on the staff was ever told" that three former pupils had travelled abroad to fight for the terror groups a nd she insisted the academy did not have a problem with extremist literature circulating in the classrooms.
She said: "We never had that to deal with as an issue. The ethos within the school which was praised by three Ofsted inspections and numerous people who came in to visit the school was one of tolerance.
"We created an atmosphere in the school where young people could talk to adults, there was always somebody that was available to talk to if they were concerned."
The former headteacher said she was not aware of Emwazi's reported involvement with gangs. She said: "He wasn't a young person that I would have thought had been involved in, at the level that has been reported, with gangs.
"He certainly didn't present like that, we certainly had no information around those sorts of things."
Emwazi later graduated with a degree from the University of Westminster, an institution which has been dogged by claims it has been targeted by Islamist extremists.
Ms Shuter was a former "super-head" who was awarded a CBE for services to education.
But she suffered a spectacular fall from grace and was handed a lifetime teaching ban when she was found to have committed expenses abuses - including splashing out £7,000 on her 50th birthday party
She can appeal against the ban in May next year.