Voice, Image Give Clues in Hunt for Foley's Killer

The Islamic militant in a video showing the death of American journalist James Foley took great care to disguise his identity, dressing head-to-toe in black, with a mask leaving only his eyes visible.

But police and intelligence services in Britain and the United States have a plethora of clues as they scramble to identify him, from image analysis and voice-recognition software to social media postings and testimony from former captives.

Prime Minister David Cameron has said the masked jihadi pictured holding a knife to Foley's throat is likely British, and...