It’s understood the man was originally from West London and was previously known to British security services.
The man first appeared in the video of the execution of American photojournalist James Foley in August last year, while his British accent led to him being dubbed 'Jihadi John'.
Mohammed Emwazi was well-known to counterterrorism officials in UK, and was prevented from flying to Kuwait in 2010. http://t.co/fO6gj6apae— Anup Kaphle (@AnupKaphle) February 26, 2015
He also featured in the videos of the deaths of fellow Western captives — US journalist Steven Sotloff, British aid workers David Haines and Alan Henning, and American aid volunteer Abdul-Rahman Kassig, formerly known as Peter Kassig.
It has been reported that the 27-year-old was previously suspected of having connections to Somali militant group al-Shabaab.
Despite the reports, British authorities have declined to comment on the man's identity.
Scotland Yard on #jihadijohn: We have asked media outlets not to speculate about investigation on the basis that life is at risk— Kate Forbes (@forbeesta) February 26, 2015
"We are not going to confirm the identity of anyone at this stage or give an update on the progress of this live counter-terrorism investigation," Commander Richard Walton of the Metropolitan Police's Counter Terrorism Command said in a statement.
The Washington Post, who quoted former friends of Mohammad Emwazi, was the first to report the identity of Jihadi John.
They reported that he moved to the UK from Kuwait at about the age of six, grew up in a fairly well off family in West London, before studying a degree in computer studies at the University of Westminster.
London Home Of Suspected Islamic State Militant Named As Mohammed Emwazi http://t.co/Pzp3zebTPI— MidEast Newz Stream (@mideastnewznow) February 26, 2015
Emwazi's first run in with British authorities is thought to have occurred in Tanzania in 2009, when he was reportedly detained by police and held overnight, after arriving in the country for a safari trip.
The Post reports that Emwazi then flew to Amsterdam after being denied entry to Tanzania, where he claimed that a British MI5 officer accused him of planning to fly to Somalia to join militant group al-Shabaab.
Not long after this incident, Emwazi moved to Kuwait and is believed to have been working in a computer company. However upon returning to the UK in June 2010, counter-terrorism officials detained him and prevented him from leaving the country.
After being detained, it's thought that he somehow managed to leave Britain for Syria at some stage in 2013, where he linked up with Islamic State militants.
He was a 'Beautiful Young man'
The director of controversial UK advocacy group CAGE, who works with people under investigation from counter-terrorism officials said Mr Emwazi was a "beautiful young man" who "tried his best" to change his situation after being informed that he wouldn't be able to return to Kuwait.
He was such a beautiful young man, it's hard to imagine his trajectory but it's not one that's unfamiliar with us #MohammedEmwazi— CAGE (@UK_CAGE) February 26, 2015
Asim Qureshi, said that he had been in contact with Emwazi since 2009 until the time he left Britain in 2013, and tried to help him work with authorities to allow him to leave the UK and return to Kuwait.
We have created an environment in the UK where security services can act with impunity #MohammedEmwazi— CAGE (@UK_CAGE) February 26, 2015
He said he couldn't be 100 percent sure if Mr Emwazi was the Islamic State jihadist known as 'Jihadi John', despite a very strong resemblance, saying that "the person I met would never have hurt a single person".
Family don't believe he is jihadi John, our last contact with him was Jan 2012. #MohammedEmwazi— CAGE (@UK_CAGE) February 26, 2015
Mr Qureshi was highly critical of what he believed were oppressive tactics from counter-terrorism officials when dealing with Mr Emwazi.
'Jihadi John' identified… And charity Cage pretty much defending Mohammed Emwazi beheading people because he had been harassed! #HeadsGone— Craig (@craig2309) February 26, 2015
"We have created an environment where security agencies can act with impunity and destroy the lives of young people," he said at a press conference held in London.
Asim Qureshi described #JihadiJohn as a 'kind, beautiful person'. Well, every brutal person has morphed from being a 'kind & loving' being.— bryaanbazaar (@infoBbazaar) February 26, 2015
After being refused the right to go back to Kuwait, Mr Qureshi said that Mr Emwazi undertook the "most incredible, persistent efforts" to try and change his situation through legal means, before eventually leaving the UK.