Only 172 people escaped from the Sewol as it sank on 16 April
Prosecutors in South Korea have detained the head of a company that owned the ferry that sank last month with the loss of more than 300 lives.
Chief executive of Chonghaejin Marine Kim Han-sik was taken into custody on Thursday morning.
Prosecutors said he faced possible charges including manslaughter and breaking maritime law.
Investigators believe the ferry was overloaded with cargo, which could have contributed to the boat capsizing.
The ferry, carrying 476 people, was sailing from Incheon to Jeju island when it sank on 16 April.
Only 172 people were rescued, with many others trapped inside the ship as it went down. Most of those on board were schoolchildren.
Investigators believe that on the day it sank, the ferry was carrying more than three times the amount of cargo it was authorised to transport.
The tragedy has caused widespread shock in South Korea, as well as criticism of the government response and a backlash over possible regulatory failure.