Prosecutors say they brought homicide charges against the ship's captain and three other crew members because they failed to carry out their duties to protect passengers when the ship was sinking on April 16.
The disaster killed 281 people, with 23 others missing.
Eleven other crew members were indicted for alleged negligence and abandoning passengers in need.
The 15 crew members, all involved in the ship's navigation, were the first group of people rescued when the Sewol was badly listing.
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