MOSCOW, January 29 (RIA Novosti) - An investigation into an accident on board a Russian nuclear submarine will be completed by March 2009, a source in the investigation commission said on Thursday.

The accident occurred late on November 8 last year while the Nerpa submarine 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.

"We will wrap up the investigation into the Nerpa accident in February and expect the case to be referred to the court as early as in March," the source said.

He added that the investigation supported the conclusion that the tragedy had been caused by mishandling of a temperature sensor on board the submarine.

A serving crew member on the Nerpa, Dmitry Grobov, has been charged with "involuntary manslaughter" and may face a sentence of up to five years in prison.

The accident on K-152 Nerpa, an Akula II class nuclear-powered attack submarine, was 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.