South Korean rescue workers operate around the area where capsized passenger ship Sewol sank during an rescue operation in Jindo April 23, 2014. [Photo/Agencies]

Several crew members, including the captain, left the ferry as it was sinking, witnesses have said, after passengers were told to stay in their cabins, even though it was time for breakfast. President Park Geun-hye said on Monday that instruction was tantamount to an "act of murder".

"The charged crew members appear to have not carried out their duty to rescue the passengers at all," prosecutor Ahn Sang-don told a briefing. "Based on the fact that they were gathered in the bridge, engine room and so on, then left the boat, we believe negligent homicide is applicable."

According to Article 10 of Seafarers' Act, a captain has to remain on board until all passengers have disembarked.

A boy with a shaking voice gave the first distress call to the emergency services when the ferry listed.

Most of those who survived made it out on deck and jumped into rescue boats, but many of the children did not leave their cabins, not questioning their elders as is customary in hierarchical Korean society. They paid for their obedience with their lives.

Lee was not on the bridge when the ship turned. Navigation was in the hands of a 26-year old third mate who was in charge for the first time on that part of the journey, according to crew members.

The wife of one crew member under investigation who did not wish to be identified quoted her husband as saying: "I should have died out there."

"He told me that he was taking some rest as he had finished his shift. He fell from his bed and struggled to open the room door to get out. He said he didn't go to the steering house to meet up with rest of the crew. Rather he was found by coastguards and was rescued.

"My husband didn't get along with other crewmen, but he told me that Captain Lee was someone comfortable and extremely calm. He said Captain Lee was like no other: he didn't drink much, although he did smoke."

Divers operate at the site where the capsized passenger ship Sewol sank in the sea off Jindo, during the search and rescue operation in the sea off Jindo, April 22, 2014, in this picture provided by South Korean Navy and released by Yonhap on April 23, 2014. [Photo/Agencies]