A faulty torpedo and not a foreign ship caused the Russian submarine Kursk to sink almost two years ago, killing all 118 people on board.
General Prosecutor Vladimir Ustinov made the announcement after meeting with President Vladimir Putin. Mr. Ustinov said the accident happened when a practice torpedo exploded inside the submarine.
The general prosecutor said the explosion caused considerable damage inside the submarine, including ripping holes in its walls, causing the vessel to sink.
The Kursk went down in August of 2000 in the icy cold waters of the Barents Sea, in Northern Russia. All 118 people on board were killed, although a small group of sailors survived the initial explosion only to perish hours later.
Russian officials at first said the accident could have been caused by a collision with a foreign submarine or a mine left over from World War II.
In June, a senior official in charge of investigating the accident said a faulty torpedo was to blame, but he did not give any of the details that the prosecutor did on Friday.
President Putin praised the investigation. The Russian president said this is the most thorough and in-depth investigation in the fleet's history.
The news of the Kursk disaster sent shockwaves throughout Russia. President Putin was severely criticized for failing to return home from vacation at the beginning of the crisis.
He later vowed to raise the remains of the submarine and determine why it went down. Since then, the bodies of 115 of the 118 people on board have been recovered and a salvage crew hired by the Russian government has raised the bulk of the Kursk.