SEOUL, South Korea - Prosecutors said Thursday they have detained the head of the company that owns the ferry that sank last month over an allegation of cargo overloading.

Senior prosecutor Yang Jung-jin said that Kim Han-sik, president of Chonghaejin Marine Co. Ltd, was allegedly aware that the ferry Sewol exceeded its cargo limit but didn't do anything before it started its trip. It sank on April 16. The sinking left more than 300 people dead or missing.

Yang said prosecutors are investigating Kim's actions to see whether they will formally arrest him.

All 15 surviving crew members involved in the ferry's navigation have been arrested, accused of negligence and failing to protect passengers. Four other Chonghaejin employees, who handled cargo on the ship, have also been arrested.