MOKPO, South Korea -- The captain of the ferry that sank off South Korea, leaving more than 300 missing or dead, was arrested early Saturday on suspicion of negligence and abandoning people in need -- three of whom were seen lifeless in the drowned vessel by a diver who was unable to get them out.

Rescuers planned 40 dives Saturday in an attempt to enter the ferry and retrieve at least some of the more than 270 people missing. A civilian diver saw the three bodies inside the ship through windows but was unable to break the windows, said Kwon Yong-deok, a coast guard official. Strong currents and rain made it difficult to get inside the ferry, where most of the passengers are believed to have been trapped, coast guard spokesman Kim Jae-in said.

So far 29 bodies have been recovered since Wednesday's disaster off the southern South Korea coast. As the last bit of the sunken ferry's hull slipped Friday beneath the murky water off southern South Korea, there was a new victim: a vice principal of the high school whose students were among the passengers was found hanged, an apparent suicide.

Prosecutors said the ferry captain, Lee Joon-seok, 68, was arrested early Saturday along with the third mate, a 25-year-old woman identified only by her surname, Park, and helmsman Cho Joon-ki, 55. Lee faces five charges including negligence of duty and violation of maritime law, and the crew members each face three related charges, according to the Yonhap news agency.

Investigators said the accident came at a point where the ship had to make a turn, and prosecutor Park Jae-eok said investigators were looking at whether the third mate ordered a turn so sharp that it caused the vessel to list.

The sharp turn came between 8:48 a.m. and 8:49 a.m., but it's not known whether it was done voluntarily or because of some external factor, said Nam Jae-heon, a spokesman for the Maritime Ministry.

Senior prosecutor Yang Jung-jin said earlier that Lee was not on the bridge when the ferry Sewol was passing through an area with many islands clustered closely together. Yang said the law requires the captain to be on the bridge in such situations to help the mate.

Yang said Lee also abandoned people in need of help and rescue, saying "The captain escaped before the passengers." Video aired by Yonhap showed Lee among the first people to reach the shore by rescue boat.

"I am sorry to the people of South Korea for causing a disturbance and I bow my head in apology to the families of the victims," Lee told reporters after his arrest, as he left the Mokpo Branch of Gwangju District Court to be jailed.

"I gave instructions on the route, then briefly went to the bedroom when it (the sinking) happened," he said.

The captain defended his decision to wait before ordering an evacuation.

A transcript of a ship-to-shore radio exchange shows that an official at the Jeju Vessel Traffic Services Center recommended evacuation just five minutes after the Sewol's distress call. But helmsman Oh Yong-seok told The Associated Press that it took 30 minutes for the captain to give the evacuation order as the boat listed. Several survivors told the AP that they never heard any evacuation order.

"At the time, the current was very strong, temperature of the ocean water was cold, and I thought that if people left the ferry without (proper) judgment, if they were not wearing a life jacket, and even if they were, they would drift away and face many other difficulties," Lee told reporters. "The rescue boats had not arrived yet, nor were there any civilian fishing ships other boats nearby at that time."

Yang said the other crew members arrested failed to reduce speed near the islands, conducted a sharp turn and failed to carry out necessary measures to save lives.

Cho, the helmsman arrested, accepted some responsibility outside court. "There was a mistake on my part as well, but the steering (gear of the ship) was unusually turned a lot," he told reporters.

Prosecutors will have 10 days to decide whether to indict the captain and crew, but can request a 10-day extension from the court.

The Sewol had left the northwestern port of Incheon on Tuesday on an overnight journey to the holiday island of Jeju in the south with 476 people aboard, including 323 students from Danwon High School in Ansan. It capsized within hours of the crew making a distress call to the shore a little before 9 a.m. Wednesday.

With only 174 known survivors and the chances of survival becoming slimmer by the hour, it was shaping up to be one of South Korea's worst disasters, made all the more heartbreaking by the likely loss of so many young people, aged 16 or 17. The 29th confirmed fatality, a woman, was recovered early Saturday.

Only the ferry's dark blue keel jutted out over the surface on Friday, and by that night, even that had disappeared, and rescuers set two giant beige buoys to mark the area. Navy divers attached underwater air bags to the 6,852-ton ferry to prevent it from sinking deeper, the Defence Ministry said.

Divers have been pumping air into the ship to try to sustain any survivors. Three vessels with cranes arrived at the accident site to prepare to salvage the ferry, but they will not hoist the ship before getting approval from family members of those still believed inside because the lifting could endanger any survivors, said a coast guard officer, speaking on condition of anonymity, citing department rules.

Police said the vice principal who was found hanged from a tree on Jindo, an island near the sunken ship where survivors have been housed, had been rescued from the ferry.

Identified as Kang Min-kyu, he was the leader of the students travelling on a school excursion. In his suicide note, Kang said he felt guilty for surviving and wanted to take responsibility for what happened because he had led the trip, according to police.

He asked that his body be cremated and the ashes scattered where the ferry went down.

The country's last major ferry disaster was in 1993, when 292 people were killed.

Chonghaejin Marine Co. Ltd, in Incheon, the operator of the ferry, added more cabin rooms to three floors after its 2012 purchase of the ship, which was built in Japan in 1994, an official at the private Korean Register of Shipping told the AP.

The official, who spoke on condition of anonymity because the matter was still under investigation, said the extension work between October 2012 and February 2013 increased the Sewol's weight by 187 tons and added enough room for 117 more people. The Sewol had a capacity of 921 when it sank.

As is common in South Korea, the ship's owner paid for a safety check by the Korean Register of Shipping, which found that the Sewol passed all safety tests, including whether it could stabilize in the event of tilting, the official said.

Prosecutors raided and seized materials and documents from the ship's operator, as well as six companies that had conducted safety checks, revamped the ship, or loaded container boxes, a sign that investigators will likely examine the ship's addition of rooms and how containers were loaded.