Transcript for 'Jihadi John' Now the Most Wanted Man In the World

Now for the global manhunt for the most-wanted man in the world. That brutal Isis executioner. We're now learning his face and name, and bit by bit how he grew from a british schoolboy to a merciless killer. ABC ease's chief investigative correspondent with the details. Reporter: New details tonight offer clues about the path from british school boy to jihad for Mohammed emwazi. At the age of 11, teachers already saw a violent streak. And he told them of his love of graphic video games, including duke nuke'em, time to kill. Ten years later, as a London college student sporting an American baseball cap, emwazi earned a degree in computer programming. And now, authorities and analysts say they believe emwazi is using those computer programming and gaming skills as part of the Isis video propaganda team. We'll begin to slaughter your people on your streets. Reporter: Not only casting himself as the front man in the gruesome beheadings, but also working behind the scenes with a group of young men with british accents and laptops, as seen in this recruitment video featuring yet another Britain recruit. Now, this is where most of the media work happens, on this little desk here. Reporter: Former hostages describe emwazi as one of four especially sadistic british captors who they nicknamed the beatles, John, George, Paul and Ringo, who especially targeted the Americans in their custody. We were together all the time even when they brutalized us. Reporter: And for all of emwazi's notoriety as Jihadi John, the former hostages say the one they called George was the true leader of the group. All four have been high on the U.S. Air strike target list even before the name of Jihadi John became public. British authorities had kept emwazi's name secret in hopes he might give away his location by trying to contact family or friends back here in London. But as of tonight, he is believed to be still alive in Syria, part of an Isis group that continues to hold at least 15 to 20 other hostages. Tom? ABC's Brian Ross in London. Brian, thank you. We now know who he is but where is he is now the biggest question. ABC's chief global affairs correspondent, Martha Raddatz, spent the day at the Syrian border where Jihadi John is supposedly hiding. Martha, the big question tonight, why can't we catch him? Reporter: Tom, the reason it's been so hard to try and find Jihadi John, is that he doesn't use cell phones. He doesn't use satellite phones, no tracking devices. Even though he taunts the west in the videos and is so bold, he's very good at hiding. An even bigger reason, we have no intelligence assets on the ground in Syria. We have lots in the skies, drones, reconnaissance, and surveillance aircraft. They can only do so much. We need somebody or something on the ground. Yet officials I speak to are confident eventually they'll find him.

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