A fierce, battle-hardened warlord with roots in Georgia and a thick red beard, Omar al-Shishani was one of the most notorious faces of the Islamic State jihadist group.
On Monday, the Pentagon confirmed that Shishani - whose real name is Tarkhan Batirashvili - died after being wounded in a US-led coalition strike in northeastern Syria earlier this month.
US officials previously said Shishani "likely died" in the strike, but reports surfaced that he had survived.
On Monday, Navy Captain Jeff Davis, a Pentagon spokesman, told AFP the US military now believed "he subsequently died of his injuries" following the strike.
Shishani, whose nom de guerre means Omar the Chechen, was one of the IS leaders most wanted by Washington which put a $5 million bounty on his head.
US officials had branded Shishani the "equivalent of the secretary of defense" for the jihadist group.
Shishani came from the ex-Soviet state of Georgia's Pankisi Gorge region, which is populated mainly by ethnic Chechens.
He fought as a Chechen rebel against Russian forces before joining the Georgian military in 2006, and fought Russian forces again in Georgia in 2008.
He resurfaced in northern Syria in 2012 as the leader of a battalion of foreign fighters, said Aymenn Jawad Al-Tamimi, research fellow at the Middle East Forum, a US think-tank.
As early as May 2013, when IS was just emerging in Syria, he was appointed the group's military commander for the north of the country, Tamimi said.
While Shishani's exact rank was unclear, Richard Barrett of the US-based Soufan Group described him as IS's "most senior military commander", adding that he had been in charge of key battles.
"He is clearly a very capable commander and has the loyalty of Chechen fighters who are considered by ISIS as elite troops," Barrett told AFP, using another acronym for IS.
Shishani was not however a member of IS's political leadership, a structure that is even murkier than its military command.
Born to Christian father
A profile of Shishani written by an IS supporter and posted online described him as "one of the best strategic and tactical leaders".
He was born in 1986 to a Christian father and a Muslim mother, according to the text, which claims he "never lost any of his battles".
In an indication of Shishani's popularity among jihadist sympathizers, the text describes him as "the new Khalid Ibn al-Walid" - a reference to a leader from the early days of Islam who played a crucial role in spreading the nascent religion in Syria and Iraq via the sword.
Observers, however, downplayed Shishani's importance.
"He was a fierce fighter," according to Rami Abdel Rahman, director of the Britain-based Syrian Observatory for Human Rights, which monitors the Syrian conflict.
"He would be sent to frontlines across IS-held territory," he said.
Still, Abdel Rahman said the impact of Shishani's death would be minimal.
"It won't have an actual impact on the battlefield. There are many other leaders," he said.
"IS chooses which faces to make known in the media - while it conceals the real leaders."