The first unmasked photo of Mohammed Emwazi -- the Islamic State group militant identified this week as “Jihadi John” -- as an adult was published Friday by a British television station.

The image, revealed by Sky News, was obtained from his student records from the University of Westminster, where Emwazi studied information systems and business management from 2006 to 2009.

Earlier this week, the Washington Post and BBC identified Emwazi, a Kuwait-born Londoner, as the militant who had been at the forefront of ISIS' media offensive. Two U.S. government sources also told Reuters that Emwazi is the militant known as “Jihadi John”.

Videos released by ISIS have shown Emwazi participating in the brutal beheadings of several Western hostages held by the group, including American journalists James Foley and Steven Sotloff. Emwazi always appeared in the videos wearing a black mask that concealed all but his eyes.

Unmasked pictures of Emwazi as a schoolboy had previously been published by the British media.

U.S. Attorney General Eric Holder vowed Friday that the Obama administration would use all means at their disposal to target Emwazi. “It doesn’t matter where you are, we’ll find you, we’ll hunt you down, and we will hold you accountable,” he said.

British Prime Minister David Cameron, while refusing to comment specifically on Emwazi's identification as the notorious militant, also said that the U.K. would take all steps necessary to put such individuals “out of action,” Reuters reported.

Western intelligence services had identified Emwazi as far back as Aug. 2014, according to reports, but had not released the information for operational reasons.