ISIS 'Jihadi John' Identity Revealed as Londoner Mohammed Emwazi

— -- "Jihadi John," the British-accented man who appeared in all black in several ISIS videos in which he appeared to behead Westerners, has been identified as Londoner Mohammed Emwazi, a former senior intelligence official confirmed to ABC News.

The Washington Post and BBC first reported the name early Thursday, with the Post citing a close friend who said he or she has "no doubt" that Emwazi is the man. A former senior U.S. intelligence official who was involved in the hunt for the man confirmed the name to ABC News.

The Post described Emwazi as being from a "well-to-do" family in London, a man who graduated the University of Westminster with a computer programming degree. The university released a statement acknowledging someone by the name left college six years ago.

British authorities have declined to comment on the man's identification. Commander Richard Walton of the London Metropolitan Police's Counter Terrorism Command (SO15) told BBC, "We have previously asked media outlets not to speculate about the details of our investigation on the basis that life is at risk."

A spokesperson for the White House National Security Council said they "are not able to confirm or deny" the reports on "Jihadi John's" identification, and referred questions to the British government.

"The U.S. government continues to investigate the murder of American citizens by ISIL [ISIS]," the NSC said. "As the President said, no matter how long it takes, the United States will not rest until we find and hold accountable the terrorists who are responsible for the murders of our citizens."

The man who would be come to be known as "Jihadi John" first appeared in a string of disturbing videos produced by ISIS last August in which he appeared to slice the necks of Western hostages, including American journalists James Foley and Steven Sotloff. By September, the FBI said it had learned "Jihadi John's" identity, but it was not revealed to the public.

A spokesperson for the Sotloff family said today the family is “confident law enforcement would find him and bring him to justice and they have full confidence the U.S. government will be able to do that.”

“They would like to see him brought to a court in New York or eastern Virginia and watch him prosecuted by a U.S. court for beheading their son and convicted to life in a super max facility,” spokesperson Barak Barfi said. “This is how justice is served in this country.”

Bethany Haines, the daughter of British hostage David Haines who was purportedly killed in one of the ISIS videos, told Britain’s ITV that identifying “Jihadi John” was a good step, “but I think all the families will feel closure and relief once there’s a bullet between his eyes.”

Sen. Angus King, a member of the Senate Intelligence and Armed Services Committees, said that by identifying “Jihadi John” it sends a message to anyone who wants to hide “because they put something across their face.”

“Somebody once said, ‘None are so brave as the anonymous.’ I think that one of the things this message says to this guy is that they aren’t going to be anonymous. I would advise this guy right now not to buy any green bananas. I think justice is going to find him,” King said.

According to the BBC, Emwazi was born in Kuwait and was "known" to U.K. security agencies. Court documents linked Emwazi to suspected extremist figures, including one man who was killed by a drone strike in Somalia in 2012, the network said.

The Post reported he's believed to have traveled to Syria in 2012.

In 2010 Emwazi reportedly attempted to move to Kuwait, but was stopped from doing so by British counter-terrorism officials.

“I had a job waiting for me and marriage to get started,” Emwazi wrote at the time to CAGE, a rights group, according to the group. “But now I feel like a prisoner, only not in a cage, in London. A person imprisoned and controlled by security service men, stopping me from living my new life in my birthplace and my country, Kuwait.”

Emwazi told CAGE he didn’t know why he was restricted from leaving the U.K. The Post reported that friends said Emwazi became increasingly desperate to leave the country after that incident.

Asim Qureshi, Research Director at CAGE, told reporters today he has known Emwazi since 2009. He could not confirm that Emwazi is “Jihadi John” and said that if he is, his personality changed greatly since Emwazi left London. Qureshi said he remembered Emwazi as a “beautiful young man” who had been harassed by British security services.

Former Director of the National Counterterrorism Center and current ABC News consultant Matt Olsen said, “The identification of this individual, if it turns out that it is in fact confirmed, really just underscores the concern that ISIS has the ability to reach into London and recruit somebody who's well-educated and comes from a middle class family."

“That's a real concern for everyone in the counter-terrorism community," he added.