A Russian mercenary—who is believed to have played a role in the killing of prisoners of war and civilians—has become the latest top military figure from Vladimir Putin’s forces to be killed in the Ukraine war.

Social media channels and Russian newspapers reported that Vladimir Andonov, 44, had been killed by a sniper in Ukraine’s second city of Kharkiv.

“He died at night during reconnaissance of the area, along with his comrade, presumably at the hands of a sniper,” said the Peleng 03 telegram channel on Sunday, in a post reported by the mass circulation Russian newspaper Moskovsky Komsomolets.

Andonov hailed from the Mogoytuysky District, Transbaikal Territory in the Siberian republic of Buryatia, whose local news outlet Gazyeta Nomer Adeen described him as the region’s “most famous volunteer” in reporting his death.