Three men and one woman were found dead in a studio apartment in Incheon on Tuesday in what police believe was a group suicide.

The men and 19-year-old woman were found in a one-room on the third floor of an apartment in Yeonsu-gu by a resident of the complex.

“It was odd that the air-conditioner was on for several days straight so we called a locksmith and went in to discover the bodies lying on the floor,” said the woman, whose identity was not disclosed to the media.

According to police, the bodies were partly decomposed, the window sills were covered with tape and there were traces of coal briquettes found.

After finding several suicide notes with detailed information about their lives and no signs of foul play, police are strongly leaning toward the possibility that it was a suicide pact, according to officials.

Police have yet to find any obvious link between the four adults, leading them to believe that the individuals met through an online forum.

Police authorities plan on sending the bodies to the National Forensic Service for further investigation.

Internet cafes and other websites that advocate suicide have been banned by portals, and a police cyber-monitoring team tracks down operators of such sites, an act that can be punishable by up to 10 years in jail.

According to government data from 2009, Korea has the highest suicide rate among all member countries of the Organization for Economic Cooperation and Development. The data by Statistics Korea shows that there are some 31.2 suicides for every 100,000 people, which also accounts for the biggest cause of death among those aged 10-40 years old.

By Robert Lee (robert@heraldcorp.com)