Russian investigators accused Igor Kolomoisky, a Ukrainian Jewish billionaire and district governor, of murder and human rights violations.
The accusation came Wednesday in a statement by Vladimir Markin, a spokesman for the Investigative Committee of Russia, a federal body that investigates serious crimes.
Besides murder, Kolomoisky is suspected of using “prohibited means and methods of warfare,” Interfax quoted Markin as saying.
Similar charges have been brought against Ukraine’s minister of internal affairs, Arsen Avakov. Their actions, Markin said, resulted in the death of more than 100 people and are the subject of an ongoing criminal probe.
The reports in Russian-language media about the opening of the investigation did not immediately include a reaction from Kolomoisky, who in the past dismissed as propaganda Russian condemnations of his actions to enforce the rule of law and to strengthen the Ukrainian army.
Kolomoisky, who became the governor of Dnepropetrovsk in March, has poured billions of his personal fortune into arming the Ukrainian army as its forces clashed with Russian troops.
Russia annexed Crimea from Ukraine in March following the ouster of President Viktor Yanukovych in a revolution that erupted over his alleged corruption and perceived allegiance to Russia.
Kolomoisky is widely credited for keeping the peace in Dnepropetrovsk, an industrial city, as pro-Russian separatists took control of parts of other cities near the Russian border. Hundreds have died in clashes with the Ukrainian army and police forces.
Separately, the Jewish mayor of Kharkiv, Gennady Kernes, returned to Ukraine Tuesday from Israel, where he underwent medical treatment following an attempt on his life in April, the Moscow Times reported.
Kernes was shot by a sniper while cycling outside Kharkiv on April 28.