Death toll from a sunken ferry off South Korea's southcoast rose to 64 on Monday as divers stepped up their search for passengersremaining missing in the disaster, the Seoul-based Yonhap News Agency, monitored here, reported.Hopes of finding any survivors were fading rapidly as none of the 302 missingpassengers have been found alive since the 6,825-ton ferry Sewol capsized and sankoff the southwestern island of Jindo on Wednesday, the report said.Of the 476 people on board, only 174 passengers, including the ferry's captain and most of its crew, were rescued as the boat listed due to what is believed to havebeen a sharper than usual turn. Monday's search efforts were expected to focus on the dining hall on the third floorof the vessel after rescue workers discovered a route to the area during the night,the government task force handling the disaster said. The dining hall has been citedas one of several areas where many of the passengers are expected to be found,along with lounges and shopping areas. It is feared to be the nation's biggest ferrydisaster since 1993, when a vessel capsized off its west coast, killing 292 people.Meanwhile, prosecutors and the police have stepped up their investigation into what went wrong and who was responsible for the sinking.On Monday, arrest warrants were issued for three mates and the chief engineer ofthe Sewol. The sunken ferry's 69-year-old captain and two other crew members were put under arrest Saturday on suspicions of negligence of duty and violation ofmaritime law. The captain has come under strong public fire after video footageshowed he was one of the first people to escape the sinking ferry.