Abdul-Khalim Saydullayev was not a familiar figure
Abdul-Khalim Saydullayev, whose death has been reported in Chechnya, was named as successor to Chechen rebel leader Aslan Maskhadov in 2005, after his death in a Russian security operation.
If Mr Saydullayev's death is confirmed, he will have been the fourth successive Chechen rebel president to have met a violent end.
Before his appointment he was a Muslim cleric little known outside separatist circles.
Even some pro-Moscow politicians in the war-ravaged republic were in the dark about him.
His obscurity led some commentators to suggest he might be a puppet of Shamil Basayev, the most influential radical figure in the separatist movement and linked to the Beslan and Moscow theatre attacks.
But he also apparently commanded some respect within the separatist movement, and rebel spokesmen described him as an old ally of Maskhadov with authority to rein in militants.
Mr Saydullayev, who was thought to be in his mid to late 30s, rose to prominence after the start of the second Chechen conflict in 1999, making religious programmes for the separatists' TV station.
Maskhadov later appointed him head of the Sharia committee, the government-in-exile's supreme court, and signed a decree passing all presidential powers to him in the event of his death.
Russian media described him as an extremist and a leading Wahhabi, a term they use to describe Islamic radicals in the region.
Speeches he released on separatist websites were couched in Islamist language.
However, Chechen analysts at the US-funded Radio Liberty characterised him as a religious conservative, far removed from the fundamentalist wing of the movement.
He was also described as a field commander and had a small armed group under his command operating around his home town of Argun, where the pro-Moscow government says he was finally killed
His wife is thought to have been killed by federal forces some years ago.