Alexander Bastrykin said the charge for Dmitry Grobov, the submariner suspected of mishandling a temperature sensor on board the submarine that caused the tragedy, carries a sentence of up to five years in prison.
Bastrykin, who heads the Investigation Committee under the Russian Prosecutor General's Office, said investigators are also considering other versions, including a technical malfunction.
The incident occurred late on November 8 while the Nerpa was undergoing sea trials in the Sea of Japan. Three submariners and 17 shipyard workers died in the accident. There were 208 people, 81 of them submariners, on board the vessel at the time.
Last week, an investigation spokesman said Grobov would undergo psychological evaluation.
The incident is the Russian Navy's worst since the sinking of the Kursk nuclear submarine in 2000, which claimed the lives of all 118 personnel on board.
