The ill-fated ferry that sank off the southwest coast killing hundreds on Wednesday made a sharp turn right before it capsized, investigators said Thursday.
The Korea Coast Guard earlier believed that the 6,825-ton Sewol struck rocks, but so far there appear to be no marks of a collision of the ferry's hull or propeller.
But on a track chart investigators found that the ferry made a sharp turn to the right around 8:48 a.m. on Wednesday.
"We're trying to find out whether the Sewol lost balance and capsized when it was making a sharp turn, considering that its center of gravity had become high as a result of an increase of cabins in the stern section," a local coast guard said.
"It's possible that the ship made a sharp turn to avoid an object suddenly looming out of the fog."
The "loud boom" that rescued passengers said they heard may have been caused by shifting cargo hitting the hull, the spokesman added.
Maritime police in Mokpo, South Jeolla Province questioned the captain of the ferry, Lee Joon-seok (69) on Thursday but he said he did not know what was going on and that he heard no sound suggesting the vessel hit a rock.
Prosecutors are considering indicting him on charges of failing to perform his duties by abandoning ship and leaving hundreds of passengers behind.