Account used to post Foley execution video identified by investigators

Voice, veins analyzed in hunt for James Foley's killer

Catherine Herridge reports from Washington

Federal investigators have identified the social media account used to post the James Foley execution video, a key “part of the forensic” trail of evidence that leads to the barbaric militants.

The jihadist who posted the video is part of a group of Islamic extremists who are active on social media platforms and are close to Islamic State leadership. Fox News has learned the name of the account, but was asked not to publish it, as it might tip off the user. The larger group frequently posts pictures of senior leadership and its “proximity” to other key militants — and a counterterrorism source close to the matter said the data suggests the operation to kill Foley, an American journalist who was kidnapped while covering the Mideast, was controlled by top ISIS leaders, with either Abu Omar al Baghdadi providing his blessing or tacit approval.

Many within the extremist group, which is now being closely monitored by U.S. counterterrorism officials, are shifting their routines to become harder to trace. They are increasingly moving away from Twitter, or using peer-to-peer message-sharing systems once typical social media accounts are shuttered.

Islamic State militants have posted another execution video since Foley’s death, this time of an Iraqi soldier with an executioner speaking Arabic. The selection of a British executioner was designed to send a message to the U.S. and Great Britain, the counterterrorism source told Fox News.

Adel Majid Abdel Bary, a 23-year-old British-born rapper, is the leading suspect in the killing. His background as middle-class and educated is consistent with the new generation of digital jihadists, sources say.

FBI and British authorities have been conducting forensic analysis on the video’s audio, studying its “audioprint” in a multi-layered approach. Secondary analysis is also being conducted on his pattern of speech, flesh tone and his left-handedness.

"Both the British intelligence service and FBI want a high degree of confidence in the match because lethal force is on the table," a U.S. counterterrorism source told Fox News.

Foley, 40, was kidnapped in 2012 while covering the Syrian uprising. The Islamic State group, formerly known as ISIS, posted a video online last week showing his killing. Foley's captors demanded $132.5 million from his parents and political concessions from Washington. A senior Obama administration official said last week that Islamic State leaders made a "range of requests" from the U.S. for Foley's release, including changes in American policy.