British intelligence has identified the black-clad figure shown getting ready to behead U.S. journalist James Foley last week, a report said. In a grisly video, the figure who has become known as "Jihadi John," said the execution was in response to the U.S. bombing of Islamic State positions near Mosul Dam in Iraq and threatened further killings.

The Times of London reported a key suspect in the killing is Abdel-Majed Abdel Bary, 23, whose family lives in a tony section of London. The Times said Bary, who recently tweeted a picture of himself holding up a severed head, left England last year.

The Times also reported a forensic team that has worked for police forces across Britain has concluded the video was likely staged with the actual killing committed elsewhere. The report said the black-clad figure might have just been a frontman.

The video released Tuesday showed Foley kneeling in the desert. He was forced to denounce the United States and its bombing campaign against the extremists, formerly known as the Islamic State in Iraq and Syria, or ISIS, before the executioner put a knife to his throat. A video of the killing was posted online.

British Ambassador to the United States Sir Peter Westmacott estimated on "Meet the Press" more than 500 people from Britain had joined ISIS.

 Sen. John McCain (R-Ariz.) said on "Fox News Sunday" ISIS presents the "greatest threat we've seen since 9/11. This has been festering for the last year and now it’s culminating with the killing and beheading of an American journalist, which I think is a turning point."

Following what the White House called ISIS' "first terrorist attack against the United States," other politicians are concerned the group may set its sights on western targets.

"They are intent on hitting the west. And there are external operations, I believe, on the way," Rep. Mike McCaul (R-Texas), chairman of the House Committee on Homeland Security, on ABC's "This Week."