Artur Sardaryan was killed on May 25, but his death was only announced today.
A spokeswoman for the Moscow region prosecutor's office says the group approached Sardaryan as he sat on a regional commuter train and stabbed him for no apparent reason.
A lawyer representing the family, Simon Tsaturyan, quotes eyewitnesses as saying the attackers shouted "Glory to Russia!"
Prosecutors have launched a hate-crime investigation.
The killing is the latest in a series of attacks on foreigners and immigrants from the Caucasus and Central Asia in Moscow and throughout Russia.
(compiled from agency reports)
Epidemic Of Hate
Yusuf Sultonov, whose 9-year-old daughter was beaten and stabbed to death in St. Petersburg on February 9, 2004 (TASS)
EXTREMISM ASCENDANT: More than half of Russians have xenophobic views, according to a report published in August 2005. In the report, rights groups say that -- despite progress in some areas -- racism, xenophobia, and anti-Semitism remain rife in Russia. But what worries watchdogs most are recent moves by nationalist-patriotic movements to form paramilitary groups....(more)
ARCHIVE To view an archive of all of RFE/RL's coverage of Russia, click here.
For a regular review of civil-society developments throughout RFE/RL's broadcast region, subscribe to "RFE/RL (Un)Civil Societies."
RFE/RL IN RUSSIAN: Visit RFE/RL's Russian-language website, featuring news, analysis, features, streaming audio, and more in Russian, courtesy of RFE/RL's Russian Service.