Matsumoto incident

The Matsumoto incident was an act of domestic terrorism perpetrated by members of Aum Shinrikyo in Matsumoto, Japan, in Nagano prefecture, on the evening of June 27 and the morning of June 28, 1994. Eight people were killed and over 200 were harmed by sarin gas that was released from several sites in the Kaichi Heights area. This incident was perpetrated about nine months before the better known Tokyo subway sarin attack.

With the help of a converted refrigerator truck, members of Aum Shinrikyo released a cloud of sarin which floated near the homes of judges who were overseeing a lawsuit concerning a real-estate dispute which was predicted to go against the cult.

The first calls to emergency officials occurred around 11:00 p.m.; by 4:15 a.m. the following morning, six people had died from the poison. On July 3, officials announced that the toxic agent had been identified as sarin using gas chromatography–mass spectrometry. The dead included Yutaka Kobayashi, a 23-year-old salaried worker, and Yasumoto, a 29-year-old medical school student. The sarin used in the incident was nearly pure.

Although an anonymous tip implicating Aum Shinrikyo was given to police after the gassing, the sect was not officially implicated in this incident until after the later Tokyo attack. One section read, "Matsumoto was definitely an experiment of sorts. The result of this experiment in an open space: seven dead, over 200 injured. If sarin is released in an enclosed space say, a crowded subway it is easy to imagine a massive catastrophe."

After the incident, police focused their investigation on Yoshiyuki Kōno, whose wife was a victim put in a coma by the gas. It was discovered that Kōno had stored a large amount of pesticide in his residence. Despite the fact that sarin cannot be manufactured from pesticides, Keiichi Tsuneishi, a Japanese historian, claimed the nerve agent is synthesizable from organophosphorus pesticides, and Kōno was dubbed by some in the media "the Poison Gas Man" and received hate mail, death threats, and intense legal pressure. After he was found innocent, every major Japanese newspaper apologized to Kōno, including those who did not name him as a suspect.