43 years ago today, April 26, 1982 (April 3, 1982, the lunar calendar), a fly caused a bloody case in Seoul. In the history of crime, serial killers and sexual killers are two different concepts. According to American law, criminals who kill two or more people in a short period of time are called "sexual killers". The time of committing crimes by serial killers is intermittent, and the interval is even as long as several decades. Sexual killers often kill randomly. There is no conflict between the victim and the murderer. The murderer only wants to "sexual indulgence". If such cases occur, it is often difficult to solve the case. Because the police cannot find clues through the life connection between the criminal suspect and the victim, and between the victim and another victim. In South Korea's modern history, the most vicious sexual killer was Yu Fan Kwan. Within 8 hours from April 26 to 27, 1982, he killed 56 people in Yi Nyeong County, South Gyeongsang Province, South Korea. He finally tied two grenades to himself and committed suicide. The reason why Yu Fan Kwan killed 56 innocent people was directly triggered by a fly that disturbed his sleep. Yu Fan Kun Yu Fan Kun was a police officer at the Seoul Police Department (present-day Seoul). He was demoted due to his violent personality and frequent drinking alcohol. He was transferred to a remote village in Inyeong County, South Gyeongsang Province to serve as a police officer. From the Seoul Police Department to the remote village, this was undoubtedly a major blow to Yu Fan Kun. His emotions plummeted. Not long after, he met a girlfriend. The two of them spent two months together and were preparing to get married. At this time, Yu Fan Kun's career was not only frustrated, The economic situation is also very bad and the pressure is particularly high. Now, on April 26, 1982, police officers in Seoul, South Korea, Yu Fan Kun was on duty at night, so he took a nap during the day. While sleeping, a fly stopped on his chest and was seen by his girlfriend next to him. His girlfriend was probably worried that the fly would disturb his sleep, so she slapped him hard on the chest and wanted to kill the fly. Yu Fan Kun, who was sleeping soundly, was awakened by his girlfriend's slap and was in a particularly bad mood. He believed that his girlfriend deliberately hit him. Yu Fankun's career was frustrated and his finances were tight. He believed that his girlfriend deliberately hit him and disturbed his sleep because of his lack of potential. The two had a fierce argument because of this. Yu Fankun's girlfriend never expected that he would cause a major disaster to the villagers of five nearby villages in order to hit a fly. In a rage, Yu Fankun ran away from home. Using his identity as a police officer, he came to the police armory and took away two carbines and seven grenades. The two carbines were also equipped with 180 rounds of ammunition. After Yu Fan Kun stole the equipment from the arsenal, he also drank a lot of whiskey. After being drunk, he first came to the local telephone office and killed three operators. In the 1980s, communication facilities in rural South Korea were still very backward. The telephone was the only communication equipment in daily life. In addition, the telephone system was not highly digitized and automated at that time, and it required manual wiring. The telephone office had no operators, which was equivalent to interrupting communication. The carbine is a relatively light rifle. Fan Kun, a pistol, held two carbines and seven grenades, knocked on doors from house to house. Because he was a policeman, the villagers thought that the police were here to do business, so they opened the door of their own house unsuspecting. Even though the door of the house itself was open, Yu Fankun entered the house without the villagers being prepared. After arriving in the house, Yu Fankun shot the villagers indiscriminately and even used grenades. After he killed some villagers in one village, he went to another village and continued to kill. In this way, he killed dozens of villagers in five nearby villages. His girlfriend was also seriously injured during random shooting and died shortly afterwards. After the case occurred, the grieving crowd was interrupted because communication was interrupted. Therefore, Yu Fankun continued to commit crimes for eight hours until the early morning of the next day when he was surrounded by a large number of police officers who came to hear the news. At around 5 o'clock, he was surrounded by the police. On a mountain, Yu Fankun, who was in a desperate situation, did not want to live at all. He tied two grenades to his body and held the three hostages he had taken, wanting to die together. With an explosion, Yu Fankun and the three hostages died. At that time, the sad crowd, Yu Fan Kun, killed 56 people in eight hours. Together with himself, a total of 57 people were killed and 35 others were injured. After the case occurred, it immediately caused a sensation in South Korea because Yu Fan Kun was a police officer. Coupled with the newspaper's description of the case at that time, words such as "police","murder","due to a fly","drunkenness", and "tragic death" frequently appeared, which aroused the panic and anger of the Korean people. They all criticized then-South Korean President Chun Doo-hwan and Interior Minister Seo Dinh Ho and demanded their resignation. After the incident, Interior Minister Seo Dinh Ho resigned, and the Interior Minister was replaced by Roh Tae-woo. Roh Tae-woo later served as South Korea's 13th President from 1988 to 1993. Therefore, this criminal case can be said to have caused a sensation throughout South Korea.