Last Updated Feb 28, 2015 8:04 AM EST
British intelligence officers are reportedly questioning teachers from the British high school of Mohammed Emwazi, who has been identified as the Islamic State of Iraq and Syria's frontman killer known as "Jihadi John."
A teacher came forward Friday night and said that Emwazi as a student had trouble controlling his anger. Now, British intelligence is trying to determine whether there was any hint of the vicious murderer he would become.
British intelligence said Emwazi was on its radar since 2009 until it apparently lost track of him about two years ago. Britain said it will search for the ISIS killers who beheaded British and American hostages.
A newly released image shows Emwazi back in 2006 as a college student in a Pittsburgh Pirates baseball cap, the menacing eyes the only facial feature visible in brutal ISIS videos.
As more images emerge, so does a clearer picture of the man and his road to radicalization, CBS News' Charlie D'Agata reports.
As a grinning elementary school student in an affluent suburb of west London, he wrote in his yearbook: "At age 30, I'll be in a football team and scoring a goal."
His university records show a competent, if not much more than average, student.
But teachers at his high school said Emwazi had to undergo anger management therapy after fighting with fellow students.
The turn toward extremism has been blamed on revenge against British intelligence services, who suspected he was trying to join terror networks. He was repeatedly interrogated, his home kept under surveillance.
Yet he slipped through the cracks and joined ISIS in 2013.
How Emwazi rose so quickly up the ranks of the terror group is shrouded in mystery, unlike the man himself.
"Now, this individual has been outed," said Sajjan Gohel, director of international security at the Asia Pacific Foundation. "He's been demasked. His aura of fear that he was trying to instill has effectively fallen by the wayside. He is going to be more intimidated next time he appears in a video. He may still be masked, but now he knows that everybody around the world knows who he is and what he's done."
British intelligence services are facing mounting questions for letting Emwazi slip the net even while they were reportedly trying to recruit him.
Prime Minister David Cameron has defended his spy agencies, rejecting claims that agents contributed to Emwazi's radicalization as "reprehensible."