The Islamic State militant known as 'Jihadi John' has been named as a young British man who was known to intelligence services.
The man who has appeared in several IS beheading videos is understood to be Mohammed Emwazi, a Kuwait-born Briton from west London.
He's thought to be in his mid-20s and to have traveled to Syria around 2012 and later joined the Islamic State.
Olly Barratt reports from London.
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His face covered in the beheading videos - his voice became known around the world and he became one of the most wanted men on the planet.
Now his identity is also known the world over.
Mohammed Emwazi - a young man from London.
And security services had been aware of him before he traveled to Syria in 2012, according to DR AFZAL ASHRAF of the ROYAL UNITED SERVICES INSTITUTE
"He'd cropped up on their radar on a number of occasions, he was associated with people that were supporting partially Al-Shabab in East Africa or gathering equipment and supplies to send to Al-Shabab… …..According to him he was approached by MI5 to become an agent for them which he found to be a form of harassment"
That characterisation of events is supported by Asim Qureshi from activist group CAGE, which campaigns against the war on terror.
He had contact with Emwazi before he left for Syria, accused UK security services of radicalising Mohammed Emwazi through harrassment.
Mr Qureshi became emotional as he spoke to a stunned London press conference of the young man he had been in contact with before he joined the Islamic State.
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The University of Westminster says it is 'sickened' to discover one of its graduates in computer studies became radicalised after his time there.
And current student Mohammed doesn't want any associations to be made.
VOX: MOHAMMED
He doesn't represent anything about Westminster as far as us in the students and he has nothing to do with Islam either as far as I'm concerned.
British security services won't publically confirm what they're thought to have known for months - that Jihadi John is in fact Mohammed Emwazi.
Their fear has been that identifying him harms investigations, and may endanger the lives of any further hostages he may be holding.
But Dr Afzal Ashraf of RUSI beleives the identification also endangers Emwazi himself.
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SUPER: DR AFZAL ASHRAF, CONSULTANT FELLOW, ROYAL UNITED SERVICES INSTITUTE
As far as the British government is concerned, their primary objective has always been to arrest and bring these people to to trial. But very often…. they often are killed within the conflict scenario, so this may well be a real concern for him, his own personal safety and the fact that he now has a sell by date on him will be a real worry for him.
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Hostages earlier released by the Islamic State say he became known as Jihadi John because he was one of three Britons guarding westerners abducted in Syria - and that that the three of them were known together as the Beatles.
And the identification of Mohammed Emwazi leads to more, but familiar, questions:
Should security services have done more to stop him, given that he was on their radar before traveling to Syria?
And how can Britain stop the flow of young people to the region to join the islamic state?
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