( CNN ) -- Australia 's navy Monday opened two weeks of hearings into the World War II sinking of the cruiser Sydney II , an effort to formally close the book on the country 's worst naval disaster . The gun turret of Sydney II was discovered with the rest of the vessel in March 2008 . The ship 's entire crew of 645 died when it was sunk by the German commerce raider Kormoran . About 15 relatives of the lost men attended Monday 's opening session , said Cmdr . Jack Rush , the lawyer presenting the evidence gathered by investigators to a commission of inquiry led by a retired judge . `` I do n't think until today -- until you actually get to hear the evidence of the impact of a bombardment of the ship and the nature of the injuries -- I think there are some pretty mixed emotions as a consequence of it , '' Rush said . The inquiry could produce its report on the sinking by April , he said . In March , researchers discovered the Sydney 's wreckage in the Indian Ocean , about 207 km ( 128 miles ) off Australia 's west coast . At the time it sank , searchers found only two floatation belts and an empty life raft -- and the only accounts of its November 1941 destruction came from survivors of the Kormoran , an armed cargo ship flying a false flag . The German ship inflicted `` enormous damage '' on the Sydney during a battle that is believed to have lasted about 35 minutes and left 70 percent of its crew dead or incapacitated , Rush said . `` It is likely that the captain , the navigator , all the senior officers were taken out on the first salvo , '' he said . A torpedo tore into the Sydney 's bow , flooding the forward end of the ship , while the Kormoran fired an estimated 87 rounds from its 15-cm ( 5.9-inch ) guns into the Australian cruiser . The Sydney limped away and sank sometime between two to four and a half hours later , Rush said . During the battle , however , the Kormoran was hit by an Australian shell that damaged its engines and set the vessel ablaze . With hundreds of mines aboard , its captain ordered the crew to abandon ship , fearing the fire would set those off . A search began only five days after the battle , when the Sydney had failed to return to port in Fremantle . And an 11-day delay by Australia 's government in announcing the ship 's loss fueled what a 1999 parliamentary report called `` a proliferation of theories '' about the fate of the crew -- that the ship was actually sunk by a Japanese submarine , that survivors were machine-gunned in the water or that the government hid bodies after they washed up on the beach . Rush said some of the proponents of those theories will be allowed to present their cases to the inquiry as well . `` We 're not hearing from everyone , but we are giving an opportunity to people to make those arguments , '' he said .
The wreckage of Sydney II was found in March 2008 off Australia 's western coast . Reports in announcing the boat 's loss in 1941 fueled various theories over the loss . Inquiry summary : Some number of theories can be allowed to present their case .