The head of Chonghaejin Marine Co. Ltd., which owns the South Korean ferry that sank last month, killing more than 250 people, was arrested Thursday over an allegation of cargo overloading, media reports said, citing South Korean prosecutors.

Kim Han-sik, CEO of the maritime company, is being charged with "causing death by negligence, as well as causing the capsizing of the ship in the line of duty," Yang Jung-jin, a senior prosecutor, reportedly said, as further investigation continues. Kim also faces charges of violating the ship safety act in connection with allegations that excessive cargo may have caused the ferry to sink. Four employees of the Chonghaejin Marine, who handled cargo on the Sewol, were arrested earlier this week.

“We’re still investigating allegations that the Sewol didn’t have enough ballast water,” Yang reportedly said, adding that Kim is being taken to Mokpo, where the investigation into the deadly ferry sinking is taking place.

About 15 of the surviving crew of the Sewol have been arrested so far, accused of negligence and failing to protect passengers.

The ferry, carrying more than 470 people, mostly school students, en route to Jeju island, about 60 miles south of the Korean peninsula, sank on April 16.

More than three weeks after the sinking, 35 people are still listed as missing. South Korea’s prime minister reportedly said Wednesday that officials must complete the search for the missing by Saturday as tidal currents were forecasted to be weak until then.

Ko Myung-seok, a government task force spokesman, reportedly said that there had been no success in recovering additional bodies since Wednesday afternoon as divers faced difficulties due to high waves and strong winds.

On Tuesday, a civilian diver fell unconscious while searching and died, while the search has been hampered by strong currents and bad weather.

According to Associated Press, the government announced Wednesday that they miscounted the number of survivors, as a coast guard chief announced that 172 people had survived – not 174, as government had been saying since April 18.

Investigators have been probing the possibility that the ferry overturned because of a cargo shift that forced the vessel off balance.

Investigators reportedly said that Chonghaejin Marine earned an extra $62,000 for the excess cargo on the April 16 voyage and about $2.9 million in extra profit for all the excess cargo that the ferry carried since March 2013.