The identity of the masked executioner seen clutching a knife in ISIS beheading propaganda videos was revealed on Thursday. A U.S. intelligence official confirmed to NBC News that a Londoner named Mohammed Emwazi is the person known as "Jihadi John." His identity was first reported by The Washington Post, which cited "friends and others with familiar with his case." The Post and the BBC reported Emwazi was born in Kuwait and is known to intelligence services. He grew up in West London and graduated from college with a degree in computer programming before traveling to Syria in 2012 and joining ISIS, the Post said.