On Tuesday, a video surfaced on YouTube showing the beheading of American journalist James Foley by a member of an Islamic militant group. Foley's executioner was shrouded in black clothing, revealing nothing but his eyes and the bridge of his nose. Without a clear image of the killer, finding him will surely be a daunting task — but it's not an entirely impossible one.

Reporter Mike Riley wrote about the logistics of the hi-tech search for the killer for Bloomberg News. The good news is, Riley explains, is that after years of intelligence-gathering in the region, investigators are "actually really good at this now."