The hunt is on for the brutal killers from the terrorist group Isis. Experts studying these eyes, the man with the british accent that executed journalist James Foley. Brian Ross has been studying the... See More
The hunt is on for the brutal killers from the terrorist group Isis. Experts studying these eyes, the man with the british accent that executed journalist James Foley. Brian Ross has been studying the all the clues and the tapes, and has the latest right now. Reporter: As outrage spread around the world today over this scene, Jim Foley's parents said they had never been prouder of their son. He was strong, courageous, loving to the end. We just recognized our little boy, he was just a hero. You know from the videos, his last words were, I wish I had more time to see my family. Reporter: U.s. And british authorities spent the day looking for clues on the video about the identity of the hooded executioner of Jim Foley. Using a database of known jihadists to look for a match with his eyes, his hands, and most telling, his voice, with what british authorities call a distinct London accent. You have plotted against us and gone out of your way to find reasons to interfere in our affairs. From what we've seen, it looks increasingly likely that is a british citizen. Now this is deeply shocking. Reporter: In the last your, hundreds of foreign fighters have joined Isis. Seizing large areas of Syria and Iraq. Now increasingly threatening to target the U.S. A former French hostage, Nicholas henlin, who was held with Foley and about two dozen over western hostages in a darkened cell for seven months, told ABC news that Foley was often singled out for harsh punishment, once for planning an escape. He had brutal punishment, including punishment inspired by the American war on terror. Reporter: There was no further word today about the other American hostage shown on the video, Stephen sotloff, who the Isis group also threatened to kill if the U.S. Bombing in Iraq continues. As the war rages on -- Reporter: Foley filed his final report from Syria for global post just before he was captured some two years ago. On location in aleppo, this is James Foley for global post. Reporter: In his final moments, James Foley faced death with the dignity and courage that marked his journalistic career. And Brian is here now. You have breaking news? Yes, about a failed rescue attempt. President Obama authorized a bold attempt into Syria to rescue Foley. But when they arrived at the site, there were no hostages present. No American casualties other than one injury. An attempt that failed. And now, the question continues.
This transcript has been automatically generated and may not be 100% accurate.