The prosecutor's office says it is examining all possible motives, including that of a racist crime.
In related news, Azerbaijan's Day.Az news agency reports unidentified attackers beat up an Azeri to death in the Russian Urals city of Novy Urengoi on April 21. The agency says the victim's body is due in Baku today.
Russia has witnessed a number of racially motivated attacks in recent months.
(ITAR-TASS, Ria Novosti, Interfax, Day.Az)