The 6,825-tonne Sewol had 29 crew, including its captain Lee Jeon-Sook.
Twenty of them escaped the ferry as it sank last Wednesday morning, and there has been public outrage at reports they were among the first to evacuate while hundreds remained trapped in the vessel.
Lee and two crew members were arrested over the weekend and charged with criminal negligence, while another four crew were taken into police custody yesterday.
Those four were paraded, heads bowed and hiding their faces, before TV cameras today.
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"We tried to gain access to the rafts but the whole ship was already tilted too much," he said.
"We tried to launch the life rafts but it was hard to get to where they were," another said.
The official death toll stood at 108 today, with 194 still missing.
Most of the passengers were high school students on a holiday trip.
One crew member, apparently an officer, suggested the ferry had a structural flaw that made it difficult to regain equilibrium once it had been lost.
The officer also mentioned "some errors" with the steering system.
The Sewol capsized after making a sharp right turn. This led experts to suggest its cargo manifest might have shifted, causing it to list beyond a critical point of return.