Ferry operator Chonghaejin Marine overloaded the ship that sank off the southwest coast last month 139 times over a period of 13 months and earned around W2.9 billion in additional fares (US$1=W1,031).
An investigator on Tuesday said since the Sewol began operations on March 15 of last year, it made 241 trips from Incheon to Jeju Island and was overloaded 139 times or six out of every 10 trips.
The Sewol's maximum cargo capacity is 1,077.5 tons, which could generate revenues of up to W26 million, but they surpassed that amount on all those occasions.
On the day of the tragedy, the Sewol was carrying 2.3 times more cargo than its maximum capacity.
Chonghaejin Marine made up to W70 million in additional revenues each trip by overloading the ferry, or a total of W2.96 billion.
As the crew escaped from the sinking ship, many passengers obeyed instructions to stay inside even though they heard rescue helicopters hovering overhead, investigators said.
Investigators analyzed text messages sent by the victims just before the ship sank, and found that they obeyed orders not to move although they knew coast guards had arrived. The ship's crew left at around 9:39 a.m., but one crewmember, identified by his surname Kang, told the passengers until 10 a.m. to remain where they were.
Investigators on Tuesday arrested another Chonghaejin Marine executive on charges of unpremeditated homicide. Investigators are trying to establish how many executives knew about the habitual overloading.