'Jihadi John' Unmasked: First Picture of Mohammed Emwazi as an Adult Emerges

— -- A day after he was identified as ISIS’s infamous “Jihadi John,” a photograph of the man, Mohammed Emwazi, has emerged, published on the front pages of British newspapers late Friday.

The image, from the files from Emwazi’s time at the University of Westminster, shows the young man in a white t-shirt and Pittsburg Pirates baseball hat. Years later, the same eyes shown in that picture would peek through a black mask as Emwazi allegedly wields a knife in multiple ISIS hostage execution videos.

“Nothing like this. We never realized he would go to be jihadi,” Sharaftullah Towsi, a friend of Emwazi’s, told the BBC on Friday, echoing sentiments from others who knew him as a “nice” young man.

But one of Emwazi’s elementary school teachers told the BBC Friday night that he was put into anger management therapy because he was getting into fights at the age of 11.

“We’d find that he’d get very angry and worked up and it would take him a long time to calm himself down,” said the teacher, who was not identified.

By the age of 21, British intelligence reportedly suspected Emwazi was interested in joining extremist groups. He was detained during a trip to Tanzania and accused of really trying to join the Somali terror group al-Shabab, according to the British activist group CAGE.

After more reported run-ins with security services, Emwazi managed to slip out of the U.K. in 2012 and make his way to Syria to join ISIS.

Emwazi came of age in London as radical Islamists were urging young men to join the jihad against the U.S. and Britain. A prominent activist, Anjem Choudary, told ABC News today he did not know Emwazi, but called him a Muslim brother whose brutal acts he refused to condemn.

“I know who I want to condemn,” he said. “I want to condemn you guys for being the tongue of the biggest terrorists in the world, the Americans and their own allies, the British.”

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. He was also seen in a video that showed the dead body of American aid worker Peter Kassig.

A month after the Foley video emerged, the FBI said it had learned "Jihadi John's" identity, but it was not revealed to the public.

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.

ABC News’ Lee Ferran contributed to this report.

ABC News' Sohel Uddin, Mike Trew, Rashid Haddou, Bruno Roeber, Randy Kreider, Alex Hosenball and Meghan Keneally contributed to this report.