The true identity of ISIS executioner 'Jihadi John' has just been revealed.

The Islamic State killer who has appeared on video beheading hostages has been named by media as former London computer programmer Mohammed Emwazi.

His name was first disclosed by the Washington Post, citing unidentified former associates, but two US government sources confirmed investigators believed Jihadi John was Emwazi.

He is reportedly from a middle-class family and earned a degree in computer programming before travelling to Syria in about 2012.

The Washington Post and BBC said Emwazi, in his mid-20s, was born in Kuwait but grew up in west London.

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According to reports, Emwazi moved to Britain at the age of six.

UK security forces reportedly chose not to disclose his name earlier for operational reasons. Police say they would not confirm or deny his identity because of their ongoing counter-terrrorism investigations.

List of killings began with journalist James Foley

Emwazi first appeared masked in a video in August when he apparently killed American journalist James Foley.

He was nicknamed Jihadi John after Beatle John Lennon due to his British accent.

He is also believed to have been responsible for the murder of American journalist Steven Sotloff, British aid workers David Haines and Allan Henning and US aid worker Abdul-Rahman Kassig.

Emwazi also appeared in a video with Japanese hostages Haruna Yukawa and Kenji Goto shortly before they were killed.

In the videos posted online, he appeared dressed all in black with only his eyes exposed and wielded a knife while launching tirades against the West.

Emwazi was identified to the Washington Post by friends and others familiar with the case, with one close acquaintance telling the paper: “I have no doubt that Mohammed is Jihadi John.”

He was described as quiet and polite with a taste for stylish clothes.

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The International Centre for the Study of Radicalisation at London’s King’s College, a leading resource for studying foreign jihadists, said it believed the identity “to be accurate and correct”.

“The fact that Jihadi John has been unveiled in this manner demonstrates that whatever efforts are made, the ability to mask one’s identity is limited or in fact impossible and their true identities will eventually be revealed,” it said in a statement.

London’s Metropolitan Police, however, would not confirm the reports.

“We are not going to confirm the identity of anyone at this stage,” Richard Walton, head of the police counter-terrorism command, said in a statement.

British media had previously suggested the killer could be a different British jihadist.

Emwazi ‘harassed by British security services’

Asim Qureshi, the research director of charity Cage which worked with Emwazi since 2009, said although he could not be certain Emwazi was Jihadi John, there were some “striking similarities”.

Cage, which campaigns for those detained on terrorism charges, said Emwazi had contacted Cage saying he had been harassed by British security services after trying to take a trip to Kuwait in 2010 where he was going to get married and had a job waiting.

“I feel like a prisoner, only not in a cage, in London…” he wrote in an email to Cage at the time.

He felt like “a person imprisoned and controlled by security service men, [who are] stopping me from living my new life in my birthplace and my country, Kuwait”.

Cage blamed his radicalisation on alleged harassment by counter-terrorism officials after he was detained in Tanzania with two friends in August 2009 when they arrived for a safari holiday.

He was deported to Amsterdam and interrogated by Britain’s MI5 domestic security agency and a Dutch intelligence officer who said he was suspected of planning to travel to Somalia and then sent back to Britain.

Cage said MI5 had tried to recruit him as an informant and a year later blocked his attempts to return to Kuwait where he had begun working for a computer programming company and planned to marry.

The charity, which also worked with Michael Adebolajo, the Muslim convert who with an accomplice killed a British soldier in London in May 2013, said both men had been victims of undue pressure from the security services.

“We now have evidence that there are several young Britons whose lives were not only ruined by security agencies, but who became disenfranchised and turned to violence because of British counter-terrorism policies,” Mr Qureshi said in a statement.

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Cage said after becoming frustrated following three failed attempts to return to Kuwait, and changing his name to Mohammed al-Ayan, he left his parents’ home to travel abroad.

Four months later, police visited the family home to say they had information he had entered Syria.

British authorities have linked Emwazi to another British militant killed in Somalia in a US drone attack.

A court ruling dated December 2011 reported Emwazi was an associate of Bilal al Berjawi, a leader of Al Shabaab, a person in possession of the court ruling said.

British intelligence officers estimate there are around 700 homegrown militants fighting for IS in Syria and Iraq.

This post was originally posted by the ABC and was republished here with full permission