A red-bearded Chechen fighter with a deep hatred of Americans has emerged as the public face of al Qaeda splinter group ISIS.
Omar al Shishani - which means Omar the Chechen - has appeared on the group's recent propaganda videos and may have been promoted to overall military chief.
He is among hundreds of Chechens who are considered some of the toughest and most ruthless jihadi fighters in Syria and Iraq.
In a video released by the group over the weekend, al Shishani is shown standing in front of black masked militants declaring the elimination of the Iraq-Syria border .
Up until recently, the 28-year-old has been considered the group's military commander in Syria, leading an offensive towards the Iraq border.
But he may now have risen to become overall military chief, a post left vacant after the death of Iraqi militant Abu Abdul Rahman al Bilawi al Anbari.
Al Shishani, whose real name is Tarkhan Batirashvili, is an ethnic Chechen from the Caucasus nation of Georgia, specifically from the Pankisi Valley.
The area is a centre of Georgia's Chechen community and once a stronghold for militants.
Former comrades say he was raised by a Christian father and Muslim mother, who died of cancer.
With a deep hatred for the Kremlin, he played a role in the 2008 Russia-Georgia War, spying on Russian tanks and relaying their positions back to Georgian artillery.
He is described by those who knew him before ISIS as a sober and respected person who did not show signs of religious extremism.
Reports suggest he rose to the rank of sergeant in the Georgian army, but was discharged after contracting tuberculosis in 2010.
He later spent 16 months in a Georgian prison after being charged for possessing illegal weapons.
It was during his time in jail that al Shishani apparently developed a deep hatred of Americans as "the enemies of Allah and the enemies of Islam".
"I promised God that if I come out of prison alive, I'll go fight jihad for the sake of God," he told a jihadist website.
As soon as he was released in 2010, al Shishani left for Turkey and later surfaced in Syria in 2013.
There, he led the al Qaeda-inspired "Army of Emigrants and Partisans", a group including many fighters from the former Soviet Union.
A meeting was soon organised with ISIS overall chief Abu Bakr al Baghdadi, an Iraqi, in which al Shishani pledged loyalty to him, say reports.
He first showed his battlefield prowess in August 2013, when his fighters proved pivotal in taking the Syrian military's Managh air base in the north of the country.
His high profile contrasts sharply with al Baghdadi, who remains deep in hiding and has hardly ever been photographed.
Al Shishani's father described his son as "a man with no job, no prospects - so he took the wrong path".
That path appears to have taken him to the upper echelons of the most formidable jihadist organisation in the world.