(CNN) -- Russian authorities have charged a sailor with "criminally negligent homicide" in the deaths of 20 people aboard a nuclear submarine earlier this month, Russian news agencies said Monday.
State-run RIA-Novosti quoted a top Russian investigator as saying that sailor Dmitry Grobov faces up to five years in prison if convicted of negligent responsibility for multiple deaths.
Last week a committee investigating the accident aboard the Pacific Fleet submarine on November 9 concluded that a crew member "for no particular reason activated the submarine's anti-fire system."
This resulted in liquefied freon gas being released into part of the submarine.
Despite the charge, RIA-Novosti quoted an investigator as saying that the possibility of other causes, including a problem with the submarine's fire-suppression system, was still under examination.
The fatal accident occurred on the vessel in the Sea of Japan. The submarine was being field tested before it became a official part of the navy, according to a Russian Defense Ministry statement. Watch Russia explain what happened »
A preliminary forensic investigation found that the release of freon gas following the activation of the fire extinguishing system may have caused the fatalities.
Seventeen of the fatalities were civilian members of the shipyard crew, the news agency Interfax reported.
The defense ministry said 208 people, including 81 soldiers were on board the submarine. In addition to the fatalities, the accident wounded 21, Russian officials said.
Although a charge has been filed, investigators are still considering other possible factors in the incident, including technical malfunction, RIA Novosti said.
The accident did not damage the submarine's reactor.
Officials have not revealed the name of the submarine, but Russian news agencies quoted officials at the Amur Shipbuilding Factory who said the submarine was built there and is called the Nerpa. Construction of the Nerpa, an Akula II class attack submarine, started in 1991 but due to a shortage of funding was suspended for several years, the reports said.
Testing on the submarine began last month and it submerged for the first time last week.
The Kremlin said President Dmitry Medvedev was told about the accident immediately and ordered a thorough investigation.
The most serious accident regarding Russian submarines occurred on August 12, 2000, when the nuclear submarine Kursk sank after an onboard torpedo explosion, killing all 118 crew members.
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