SEOUL, April 23 -- South Korean prosecutors on Wednesday raided the house of the sunken ferry's owner house and affiliates of the ship's operator for alleged corruption and wrongdoings in running the vessel.

A special prosecutor team, which has been investigating into alleged illegalities of the ship's operator, raided home of the ship's beneficial owner, known as Yoo Byung-eon, local media reported.

Prosecutors also raided houses of his two sons and offices of Chonghaejin Marine's affiliates as well as a religious community supposedly linked to Yoo.

Yoo, 73, is a former chairman of the Semo Group, which went bankrupt in 1997, local daily Jungang Ilbo reported.

Prosecutors investigated Yoo in 1987 on suspicion that he could be behind a mass suicide of 32 pseudo-religious believers. At that time, he acted as a minister of the apocalyptic pseudo- religion.

Assets owned by Yoo were estimated at 560 billion won (540 million U.S. dollars). Prosecutors have been tracing bank accounts and foreign real estates purchased by Yoo and his two sons, including a 3.5-million-dollar mansion in New York owned by his second son.

Investigators confiscated financial documents, internal reports and computer hard discs from around 10 places to investigate alleged illegalities in running the Sewol ferry, which capsized and sank off Jindo Island in the country's southwestern coast on April 16.

The 6,825-ton Sewol ferry departed around two and a half hours late than scheduled from the country's western port city of Incheon, where other ships delayed their departures due to a heavy fog.

The ship, which was built in Japan in 1994 and had no accidents for 18 years there, was modified by the ship's operator to expand passenger cabins and raise the total capacity including crew by 116 people to 956.

The 476 passengers aboard the ship were nearly half the maximum capacity, but it was offset by an overloaded cargo. The vessel was loaded with 180 cars and trucks and 1,157 tons of freight, far exceeding the reported figure of 150 vehicles and 657 tons of goods.

The ferry, which was en route to the southern resort island of Jeju, capsized and sank in waters notorious for swift currents. When the ship began tilting heavily to one side, captain was not at the helm and the wheel was handed over to the third mate who conned the ship in the waters for the first time.

The most decisive factor was negligence of duty by some crew members, including the captain who abandoned the vessel and was among the first group saved when the ferry tilted so heavily that passengers were unable to move.

The 69-year-old captain was arrested Saturday over five charges including negligence of duty along with the third mate and the helmsman who conned the ship when the ship sank.

Four more crew members, including two first mates, one second mate and one chief engineer, were also arrested on Monday over negligence of duty and violation of rescue acts charges.

President Park Geun-hye has instructed prosecutors to investigate all processes from how the ship was imported and given a license, to whether the ship was modified, how often safety checks were made and how the sailing was approved.

Park said that those responsible for the disaster "will have to take criminal and civil responsibilities regardless of ranks," saying that those responsible should be disclosed stage by stage.