The FBI said on Thursday it has identified the man behind the beheading videos of hostages James Foley Steven Sotloff and David Haines.The name and nationality of the masked man, featured in the three videotaped executions, was not revealed by FBI Director James Comey, who spoke to journalists at the agency's headquarters in Washington DC. A British-accented man is believed to be behind all three decapitations, set in a desert, with the captives clad in bright orange jumpsuits.The FBI chief also said that many Americans fighting with rebels in Syria have returned to the United States. The string of videos began after the US launched air strikes in Iraq in July. Islamic State has declared a caliphate across chunks of northern Iraq and Syria it has seized from tribes and authorities.Each of the three videos opens with a direct address to a world leader, before the victim pins the blame for his pending death on his government – be it US President Barack Obama or British Prime Minister David Cameron – and is beheaded by the notorious masked fighter. Previous reports in British media suggested the man behind the gruesome decapitations was a former London-based rapper known as Abdel-Majed Abdel Bary.