LONDON — The knife-wielding masked ISIS militant seen in a number of beheading videos and dubbed “Jihadi John” has been named as Mohammed Emwazi, a London man with a college degree, a U.S. intelligence official confirmed to CBS News Thursday.

Emwazi earned his degree from the University of Westminster, the official told CBS News.

Both The Washington Post and the BBC reported Thursday that he was known to British security services by 2011 at the latest.

Friends of Emwazi spoke to the Post on condition of anonymity, including one who said that they had “no doubt” Emwazi was the man who appeared in execution videos of Foley and American journalist Steven Sotloff and American aid worker Peter Kassig.

The research director at a British human rights group also told the Post that he believed Emwazi was the man in the videos.

“There was an extremely strong resemblance,” Asim Qureshi told the Post. “This is making me feel fairly certain that this is the same person.”

Emwazi’s family wouldn’t comment to the Post. Neither would U.S. officials.

Referring to ISIS by an acronym for the Islamic State of Iraq and the Levant, or ISIL, a spokeswoman for the U.K. Embassy in Washington told the Post, “Our prime minister has been clear that we want all those who have committed murder on behalf of ISIL to face justice for the appalling acts carried out. There is an ongoing police investigation into the murder of hostages by ISIL in Syria. It is not appropriate for the government to comment on any part of it while this continues.”

Emwazi’s friends told the Post that they believe that a planned trip to Tanzania in May 2009 led to his radicalization.

Emwazi and two male friends were detained by police upon their arrival in Dar es Salaam, stayed in custody overnight and were eventually deported, the Post reported.

Emwazi then went to Amsterdam. According to emails that he sent to Qureshi, which were provided to the Post, Emwazi claimed that an officer there from the British Security Service, known as MI5, accused him of trying to go to Somalia, where the al Qaeda-linked terror group al-Shabaab is based.

Emwazi claimed MI5 then tried to recruit him, the Post reported.