The assailant of the attack on South Korean opposition leader Lee Jae-myung, identified as 67-year-old Mr. Kim, was found to have carefully prepared for the crime, according to a police investigation on Jan. 3. He purchased and modified the weapon used to stab Lee, and conducted a thorough investigation of Lee’s movements. Police filed an arrest warrant for Kim on the same day on suspicion of attempted murder.

Kim traveled to Busan by KTX from Asan, South Chungcheong Province, the day before the crime and then traveled to Ulsan by train on the same day. Ulsan Station is the closest train station to the village of Pyeongsan, where Lee planned to go. The next day, on Jan. 2., Kim approached Lee at the site of a new airport in Gadeokdo in Busan, pretending to be a supporter, and stabbed him in the neck, and was arrested by police shortly afterward.

All of these acts, which are considered “political terrorism,” were carried out by Kim alone. “This is a typical pattern of behavior for ‘reclusive political hooligans,’” experts say. In that he was so obsessed with politics that he followed a politician and attempted to kill him, he was similar to a hooligan who would go on a rampage on and off the field and engage in violent acts because of his support or dislike for a particular soccer team. He is also said to be a “lone wolf” terrorist, meaning that he does not belong to a pack and prepares and executes his attacks alone.

Testimony from Kim’s neighbors backs this up. A real estate agent, Kim was remembered as a man who locked himself in his office and played Go (an abstract strategy board game) online all day. “He didn’t talk much and didn’t drink,” said a real estate agent, while a relative of Kim’s said he “didn’t come around much, even though he lived in the same neighborhood.”

Kim said he enjoyed watching political YouTube videos despite the distance he had from his neighbors. The store owner near Kim’s office said, “When he came to buy things, he would watch political YouTube videos with the volume turned up loud,” adding, “He was a little bit introverted, so there was no other conversation.” Police are also forensically examining Kim’s phone to determine which YouTube channels he usually watches.