Prosecutors in the western port city of Incheon are probing Yoo Byung-eon and his two sons, the titular owners of ferry operator Chonghaejin Marine, on charges of embezzlement, breach of trust, tax evasion, illegal foreign currency dealing, extortion and bribery.
Chonghaejin operated the ferry Sewol that sank off the southwest coast last Wednesday with hundreds of passengers trapped aboard.
Prosecutors also slapped travel bans on around 30 executives in various companies owned by Yoo and his sons. That means over 60 employees of Chonghaejin Marine have now been banned from leaving the country for various reasons.
Prosecutors are investigating whether the Yoos, who have more than W240 billion in assets, pressured staff of the cash-strapped ferry operator to cut costs and forgo crucial safety measures.