JINDO, South Korea: Investigators sought arrest warrants Friday for the captain of a South Korean ferry that capsized two days ago, as divers overcame strong currents and near zero visibility to enter the submerged vessel for the first time.
The confirmed death toll from the disaster stood at 28, but the focus of concern remained the 268 still missing as relatives clung to increasingly slim hopes that some may have survived in air pockets.
The unfolding tragedy was compounded by the apparent suicide of a high school vice principal who had been rescued from the 6,825-tonne Sewol that sank Wednesday morning with hundreds of his students trapped inside.
The coastguard said a joint investigation team of police and prosecutors had applied for arrest warrants for the ferry's captain, Lee Joon-Seok, 52, and two of his crew.
The charges were not specified.
Earlier, prosecutors said Lee had handed the helm to his third officer before the ferry capsized.
The breakthrough by dive teams in finally accessing the ship came more than 48 hours after the 6,825-tonne Sewol went down -- a delay that has incensed the relatives of those still unaccounted for.
After several attempts, two divers managed to pry open a door and enter the cargo section on Friday afternoon, a senior coastguard official said.
Hours later another two-man team accessed one of the cabins, but found nothing.
"The search operation will continue through the night," the official said.
"Visibility is almost non-existent. You can hardly see your hand in front of you face," said one diver when he returned to the harbour at nearby Jindo island.
Of the 475 people on board the Sewol, only 179 were rescued and no new survivors have been found since Wednesday.
Three giant, floating cranes reached the rescue site, but regional coastguard commander Kim Soo-Hyun stressed they would not begin lifting the multi-deck ferry until they were sure there were no survivors inside.
"I want to be clear: There won't be any salvage work done against the will of the families," Kim aid.
More than 350 of the passengers were students from Danwon High School in Ansan city just south of Seoul.
Among those parents whose children were still missing there was bitter resentment at what they saw as the inadequacy of the official response.
"It's been two days but no one has been brought out alive," complained Lee Yong-Gi, whose son was unaccounted for.
"I firmly believe that the kids are alive. We need to rescue them as soon as possible. But officials are dragging their feet," Lee told AFP.
Local police said they found the body Friday of Danwon High School vice-principal, Kang Min-Kyu, who had managed to escape the Sewol as it sank.
Multiple local media reports said he had been found hanging by his belt from a tree, and Yonhap news agency cited a suicide note police found in his wallet.
"Surviving alone is too painful... I take full responsibility," the note said.
Captain Lee and his 28 crew, most of whom survived the disaster, have been heavily criticised after reports that they were among the first to abandon ship.
"The captain was not in command when the accident took place," prosecutor Park Jae-Eok told a press briefing.
"It was the third officer who was steering the ship," he said.
The captain had apologised Thursday to the victims and their relatives, but offered no clear explanation for what caused the Sewol to capsize.
Tracking data from the Maritime Ministry showed that the ferry made a sharp turn just before sending its first distress signal.
Some experts believe a tight turn could have dislodged the heavy cargo manifest -- including more than 150 vehicles -- and destabilised the vessel, causing it to list heavily and then capsize.
But others suggested the turn might have been caused by a collision with a rock or other submerged object.
Chief prosecutor Lee Seong-Yoon stressed there was "no limit" to the range of the investigation.
"We will make sure... those responsible are sternly held accountable," Lee said.
As well as the cause of the disaster, investigators will be looking at why passengers were ordered to stay in their cabins and seats for up to 40 minutes after the ferry ran into trouble.
Furious relatives believe many more people would have escaped if they had reached evacuation points before the ship listed sharply and water started flooding in.
Newspaper editorials were scathing with the Dong-A Ilbo daily calling the rescue response "ludicrous".
"We have the world's finest shipbuilding industry in the 21st century, but our mindset is in the 19th century," the newspaper said.