A Vladivostok jury on Friday acquitted two Navy sailors of wrongdoing in the deaths of 20 people on the Nerpa nuclear submarine in 2008.
Prosecutors had accused Dmitry Grobov, an engineer, of negligence in accidentally switching on the submarine's fire-fighting system, causing freezing Freon gas to pour into the vessel. The deaths were blamed on the inhalation of the fumes.
The other defendant, submarine commander Dmitry Lavrentyev, was accused of abuse of authority for not training his crew properly.
Both sailors were acquitted by a jury on Sept. 14, 2011, but the Supreme Court's military board overturned the verdict in May 2012 and ordered a new trial.
Lavrentyev could have been jailed for 10 years if convicted, while Grobov had faced five years in prison.
Lavrentyev and Grobov, who had maintained their innocence, said they were happy with Friday's outcome. Lavrentyev also expressed hope that he will be allowed to commandeer a submarine again.
Many media outlets, including Novaya Gazeta, have published reports questioning whether the inquiry was properly conducted.
Pacific Fleet prosecutors said the jury's ruling was "largely emotional" and that they would appeal.
The Nerpa accident was the worst to hit the Navy since 118 sailors died in the Kursk nuclear submarine disaster in 2000.
In August 2010, the Nerpa submarine was handed over to India on a 10-year lease.