'Jihadi John' from Islamic State beheading videos unmasked as Londoner

A masked, black-clad militant, who has been identified by the Washington Post newspaper as a Briton named Mohammed Emwazi, brandishes a knife in this still image from a 2014 video obtained from SITE Intel Group February 26, 2015. REUTERS/SITE Intel Group/Handout via Reuters

LONDON/WASHINGTON (Reuters) - The masked "Jihadi John" killer who fronted Islamic State beheading videos has been identified as Mohammed Emwazi, a British computer programming graduate from a well-to-do London family who was known to the security services.

The black-clad militant brandishing a knife and speaking with an English accent was shown in videos released by Islamic State (IS) apparently decapitating hostages including Americans, Britons and Syrians.