The South Korea ferry likely capsized when it turned at too high a speed, prosecutors said Monday as the death toll climbed to 87, with 215 still missing.
In an arrest document, the captain was charged with undertaking an "excessive change of course without slowing down" while traversing a channel off South Korea's southwestern tip. He was also charged with negligence in evacuating passengers.
Lee Joon-seok, 68, and his fellow crew members were accused by the country’s president of "unforgivable, murderous behavior" for telling passengers to stay in their rooms and for waiting more than half an hour to give the evacuation order. "Legally and ethically, this is an unimaginable act," said Park Geun-hye.
Prosecutors on Monday announced four more arrests — two first mates, one second mate and a chief engineer.
Fishermen and others who navigate the tidal waters around Jindo island where the Sewol started to sink last Wednesday told Reuters the route followed by the ferry from the port of Incheon to Jeju was regularly used by ferries and larger vessels such as oil tankers.
There were few navigation risks in the main channel, they said. The Korean Meteorological Association said there was a 0.5 meter swell. It was cloudy, but there was no fog.
Han Sang-sik, head of the Jindo office of the Dadohae Haesang National Park — an area covering 1,700 islets — said the channel in the spot where the Sewol sank was 122-142 feet deep and the channel itself was two miles wide, offering plenty of room for maneuver.
"People living in nearby islands say fishing boats tend to avoid the area at full moon as the current is especially strong at that time," he said. There was a full moon the night before the accident.
But that should not have been an issue for the Sewol, with a gross tonnage of almost 7,000 metric tons and one of the largest passenger ferries in operation in Korean waters.
The accident happened when the ship made an abrupt turn and began to list sharply. It was not clear if the sudden change of direction was one of two scheduled course changes to navigate the channel.
Witness reports say cargo started to shift on the foredeck, but it was not clear whether that caused the boat to list after the turn or was a consequence of the listing. Moon Ki-han, an executive at Uryeon, the firm that undertook supervision of cargo loading, told Reuters there were 105 containers onboard. Of these, 45 were loaded on to the front deck and 60 into the lower decks. In total, the ship was carrying 3,600 metric tons of cargo including containers, vehicles and other goods.
One of the lines of investigation is that a sharp turn could have caused the cargo to shift, which in turn could have contributed to the swift capsizing of the ship. Investigators have seized the records of Uryeon and the ship owner.
The captain was not on the bridge at the time of the initial listing, not unusual on a 13 1/2-hour voyage. Navigation was the responsibility of a 26-year-old third mate.
Transcripts of the distress calls from the ship, released on Sunday, illustrate the confusion and delay that ensued after the vessel began to list.
There were 476 passengers and crew on board, and 174 were rescued as the vessel began to sink. South Korea’s Yonhap news agency reported Monday that the confirmed death toll had risen to 87, with 215 missing.
Reuters and The Associated Press contributed to this report.