Who is Islamic State’s Mohammed Emwazi?

He is the knife-wielding militant who appeared in a string of macabre beheading videos.

It is not yet known whether a U.S. drone strike targeting a vehicle in Syria on Thursday killed Mohammed Emwazi, Islamic State’s most notorious executioner. If so, it would be a publicity coup for the American-led coalition battling the militants -- although it is not expected to have a major impact on the battlefield.

Nicknamed “Jihadi John” in the world’s media, the 27-year-old British citizen became the subject of an international manhunt when he was featured in videos announcing the slayings of foreign hostages including American journalists James Foley and Steven Sotloff.

Former captives said he was one of several British-sounding guards they dubbed “the Beatles.” His nickname is a reference to Beatles member John Lennon.

“He was one of the worst, who hit and tortured without any restraint,”Didier François, a journalist held for 10 months in Syria, told his French radio station Europe 1.

Born in Kuwait, Emwazi was brought to Britain by his family when he was 6. He attended schools in affluent parts of northwest London, where he was remembered as generally quiet and hard-working.

Teachers at Quintin Kynaston Academy told reporters that Emwazi had faced bullying at school and had difficulty keeping his emotions in check. But they said he had received anger management classes, which appeared to help.

He graduated from the University of Westminster in 2009 with a degree in computer programming.

The transformation of the soccer-loving schoolboy into the face of Islamic State brutality raised questions in Britain about the country’s role as an incubator of Islamist extremism.

An advocacy group that assists British Muslims in trouble with the law suggested that harassment by the security services helped drive Emwazi into the arms of Islamic State.

Emwazi contacted the group, known as CAGE, when he was detained in Tanzania with two friends in summer 2009 and sent back to Britain, interrupting what he said was a vacation after completing his studies.

Emwazi told the group he was suspected of attempting to join the Somali militant group Shabab and repeatedly questioned by British security officers. On one occasion, he said, he was thrown against a wall, his beard was grabbed and he was choked.

The attention of the British authorities later prevented Emwazi from moving to Kuwait, where he said he had a job waiting, and cost him two fiancees, according to CAGE research director Asim Qureshi.

Court documents obtained by the BBC , however, suggested that Emwazi may already have been associating with suspected radicals. The documents filed in 2011 allege that Emwazi was part of a group that some intelligence analysts called the North London Boys, which had been funneling equipment, funds and fighters to the Shabab.

Emwazi is believed to have left for Syria around 2013. He first started grabbing headlines in August 2014 when he appeared in a video purporting to show Foley’s killing, his face hidden behind a black balaclava and speaking in British-accented English.

In the video, he condemns U.S. airstrikes and warns President Obama that any attempt to “deny the Muslims their rights of living in safety under the Islamic caliphate will result in the bloodshed of your people.”

Foley recites a statement calling the U.S. government his “real killers” before he is beheaded off-camera.

Similar videos were released after the deaths of Sotloff, British aid worker David Haines, British taxi driver Alan Henning, U.S. aid worker Abdul Rahman Kassig and Japanese journalist Kenji Goto.

Emwazi was publicly unmasked as their executioner in February; British authorities had already been aware of his identity for several months.

Emwazi’s video appearances earned him celebrity status in militant circles and were a powerful recruiting tool for Islamic State.

But a man who came across Emwazi around that time described him to the BBC as a loner who set himself apart from other militants.

“He was cold. He didn’t talk much. He wouldn’t join us in prayer,” said the man, identified by the nickname Abu Ayman.

“Some love him,” the man added. “Some joined [Islamic State] after watching and admiring him; they take him as an example.”

But others, he said, “think he is showing off.”

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