Four man were convicted of killing a student from Congo and were sentenced to prison.
Epassak's killing came amid a wave of attacks on dark-skinned foreigners and immigrants from Central Asia and the Caucasus region in recent years, many of them in St. Petersburg. His death prompted African students and local residents to protest against hate crimes.
Tuesday's verdict followed a repeat trial which came after a jury's decision last July to acquit the four man, which was appealed by prosecutors.
Also on Tuesday, a court in Moscow sentenced three members of a Russian neo-Nazi group to prison sentences ranging from four to six-and-half years for lethally stabbing a man heading to a rock concert, RIA Novosti news agency reported.
So far this year, 31 people were killed and another 203 wounded in apparent hate crimes, according to the Sova analytical center that monitors hate crimes.
Rights groups say authorities do little or nothing to combat xenophobia, often prosecuting hate crimes as simple hooliganism.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?