Reactions to the recent suicide of the singer U;Nee once again highlighted one of the more unsavory aspects of Korea's Internet culture, which is dominated by so-called "cyber warriors" who produce malicious comment professionally.

"This is the first news that made me smile in a long time," one comment read after the singer took her own life on Jan. 21, apparently after being depressed due to malicious online comment for some time. A batch of malicious messages were posted immediately to mock her death.

Last year, the Cyber Crime Investigation Division of the Seoul Metropolitan Police investigated a man who had posted hundreds of messages a month against a political party online. A police officer said the man spent all his time, except when he was asleep, at the keyboard. "We were surprised to find him more timid than ordinary people despite the aggressive nature of his postings," he said.

It is difficult to generalize about keyboard warriors because their Internet ID reveals nothing about their jobs, ages or demographic characteristics. But cyber crime investigators say those who have been caught are typically timid and softly spoken, and are either still at school or jobless.

Many live alone in studio apartments. They are not in principle against certain political parties or certain celebrities. Rather, they tend to post malicious comment on any news item that attracts their attention, and regardless whether it is political, economic or entertainment news. They believe they are targeting people in the news, with no intention to cause personal harm.

Prof. Namkoong Kee, a psychiatrist at Yonsei University's Severance Hospital, said, "Passive-aggressive people are easily tempted to take pleasure in posting malicious online messages. People who can't express their anger in the real world tend to become abnormally aggressive in a space where they believe they can hide behind anonymity and from a safe distance."

A memorial service was held Monday in Onnuri Hospital, Incheon for U;Nee, a singer and actress who committed suicide on Jan. 21.

In 2005, a 32-year-old man found his identity revealed on the Internet after his girlfriend committed suicide, and was harassed by malicious online comment. Everything about him -- school, names of family and friends -- was exposed. His website was inundated with messages that called him "shameless" and said he let his girlfriend die. He asked the police to investigate. "I met them to file a lawsuit," the victim said. "I was perplexed to find most of the keyboard warriors were ordinary college students or office workers. They even said sorry."

He sued not only the perpetrators but also four portal sites including Korea's biggest Naver and Daum, which disseminated the messages. The district court is expected to pass judgment on Feb. 2. The victim believes portal sites are responsible because they provide Netizens with a space to spread their slander.

Byun Hee-jae, who heads a group of victims of malicious online comment, agrees. The victim "was virtually condemned to social death by Internet," he says. "We sued the portal sites as well because they were responsible for allowing Netizens to post these messages."