"According to the investigation, in 1998 [Sulim] Yamadayev... organized the abduction and murder of a Chechen businessman," said Vladimir Markin, spokesman for the Investigation Committee of the Russian Prosecutor General's Office.
On Wednesday, Chechen Interior Minister Ruslan Alkhanov told Ramzan Kadyrov, the president of the troubled North Caucasus republic, that Yamadayev had been put on a federal wanted list, but the information had not been confirmed.
Chechen investigators say a probe into murder charges against Yamadayev and some of his commandos was opened May 4.
Yamadayev is suspected of being behind an attack on Kadyrov's security convoy in Chechnya on April 14.
The Vostok battalion answers directly to the Russian Defense Ministry and the Chechen authorities have no effective control over it.
Kadyrov said previously he had no conflict with Vostok itself, but had concerns about some of its military leaders, whom he dubbed criminals.
Badrudi Yamadayev, Sulim's younger brother, was sentenced in 2003 to 11 years in prison for attempted murder, but was later released on parole. He is currently wanted by law enforcement bodies.
Kadyrov has accused the Yamadayev brothers of a number of crimes and demanded that they be brought to justice.
The Chechen president explicitly pointed to a special military operation by Vostok battalion troops in the Borozdinovskaya village in the summer of 2005. Four houses were burnt down, 11 people disappeared and a 77-year-old man died as a result of the operation.
