Kang Min-gyu, 52, had been missing since Thursday, but was found dead yesterday.
Police said Kang did not leave a suicide note, with the alarm raised after he was reported missing by a fellow teacher. He was rescued from the ferry after it capsized.
Twenty-eight people had officially been declared dead before Kang’s suicide and 179 were rescued.
The overwhelming majority of the missing are students from the Danwon High School on the outskirts of Seoul, who were on a holiday trip to the island.
Divers are fighting strong tides and murky waters to get to the sunken ship but the likelihood of finding any of the missing alive is slim.
At the high school in Ansan, an industrial town near Seoul, many friends and family of the missing gathered in sombre silence, with occasional sounds of sobbing breaking the quiet.
“When I first received the call telling me the news, at that time I still had hope,” said Cho Kyung-mi, who was waiting for news of her missing 16 year-old nephew at the school.
“And now it’s all gone.”
In the classrooms of the missing, fellow students have left messages on desks, blackboards and windows, asking for the safe return of their missing friends.
“If I see you again, I’ll tell you I love you, because I haven’t said it to you enough,” reads one message.
Warrant for captain’s arrest
Prosecutors have requested arrest warrants the captain of the ferry, as well as two other crew members.
The investigation into the ferry disaster has focused on the sharp turn it took just before it started listing and whether a quicker evacuation order by the captain could have saved lives.
Investigators are also trying to determine whether the captain abandoned the ship.
Rescuers are struggling to find about 270 people still missing and feared dead.
At least 28 bodies have been recovered.
Officials said there were 179 survivors and about 270 people remain missing.