South Korean prosecutors investigating a ferry disaster said on Sunday they would seek to extend the detention of the ship's captain and two other crew by 10 days as they tried to determine the cause of an accident that may claim more than 300 lives.
The ferry, the Sewol, was on a 400-km (300-mile) voyage from Incheon to the southern holiday island of Jeju in calm weather when it turned, listed sharply and then began to sink early on Wednesday.
The ship was being steered by the third mate, on her first passage helming through the waters, and the captain was not on the bridge at the time.
Out of the 476 passengers and crew, 339 were pupils or teachers from a high school in Ansan, a commuter city outside Seoul.
Divers gained access to the passenger quarters of the sunken vessel overnight for the first time and by midday on Sunday the total of confirmed deaths to had risen to 50, with 252 passengers, most of them children, still missing.
The 20-year old ferry took more than two hours to sink but passengers were ordered to stay put in their cabins. So far, 174 passengers are known to have survived the capsize.
"We are trying to find out if there is additional negligence," Prosecutor Yang Joong-jin told a news conference in Mokpo, one of the centres for the investigation.
When the crew were arrested on Saturday, they were detained by police for 10 days and prosecutors for a further 10. If the extension is granted, they could be detained for 30 days.
Yang said that prosecutors had also summoned 10 other people to give evidence, including other crew from the Sewol and officials from the ferry's owner,Chonghaejin Marine Co Ltd.
The death toll mounted steadily on Sunday as more divers gained access to the passenger quarters of the ferry with the help of ropes to guide them through the murky water.
"We are now putting in four guide lines, before there was only one, so their access will become faster," Ko Myung-suk, a coast guard official, told a news briefing in the rescue centre in the port of Jindo.
A naval sailor also died on Saturday on a boat on the way out to help in the search, a naval official said.
ANGUISH AND FRUSTRATION
Relatives of those still listed as missing, but who are now presumed to be dead, clashed briefly with police when about 100 of them tried to leave the island by a road bridge to the mainland to take their protest to the capital city of Seoul.
Police blocked them and they later turned back.
"Bring me the body," weeping mother Bae Sun-ok said of her child as she was comforted by two policemen at the bridge.
More than 500 parents of the school children and relatives of other people missing have spent four days and nights cooped up in a gymnasium in the port city of Jindo, which is the centre of the rescue operations.
Tempers have frayed over the slow pace of the recovery and frequent changes in information.
President Park Geun-hye was booed by some of the relatives when she visited the gym on Thursday.
Captain Lee Joon-seok, 69, was arrested on Saturday on charges of negligence for quitting the ship while leaving passengers on board along with two other crew members, including the third mate.
Lee told television cameras when he was arrested that he feared passengers would be swept away by the strong tides in the area and did not order a general evacuation.
He has not said why he left the ship when the passengers were instructed to remain on board.
Pupils at the school in Ansan, a gritty commuter town, set up shrines to the dead and posted messages for the missing.
The vice-principal of the school, who was on the ferry and survived the capsize, hanged himself outside the gymnasium in Jindo in another blow to the school and his body was discovered on Friday.
The sinking looks set to be the country's worst maritime disaster in 21 years in terms of loss of life.
(Additional reporting by Chookyung Kim and Sanggyu Lim; Writing by David Chance; Editing by Sandra Maler and Robert Birsel)