Man in his 70s set fire to two Gangnam buildings over patent dispute, had prepared 3 days in advance

A man in his 70s suspected of setting fire to two buildings in Yeoksam-dong, Gangnam-gu, Seoul on Tuesday — injuring more than 10 people — is believed to have carried out the attacks out of grievances against a patent law firm he had hired to register a trademark overseas. Police said they plan to investigate the motive and method of the crime in detail.

The suspect, identified only as A, had commissioned the patent law firm — one of the buildings he targeted — to register a trademark abroad. The firm told him that only an online certificate would be issued, given the nature of the country where registration was sought, but A reportedly demanded a paper certificate and came to suspect that the patent attorney was stealing his trademark.

After his arrest Tuesday, A shouted to reporters as he entered Suseo Police Station around 6:15 p.m. that he had committed the attacks "because the patent law firm defrauded me."

Asked whether he had harbored ill feelings toward the firm, he said, "I filed a patent back in 2000, and they committed fraud," while holding up a printout of text message exchanges and urging reporters to photograph it.

The printout contained a message reading, "We should have sent you this document — please consider this your certificate of registration." The message appeared to have been sent by the patent law firm.

When asked how long he had been planning the attack, A said, "Preparing? About three days." Asked whether he had anything to say to the victims, he replied, "Tell them to stop committing fraud."

A is suspected of setting fire to the third floor of the Sinmyeong Building in Yeoksam-dong at around 11:54 a.m. Tuesday, and then to the fourth floor of the Hanyang Building, also in Yeoksam-dong, at around 12:01 p.m. Both locations housed patent law firm offices.

CCTV footage captured A leaving his residence in Gangseo-gu that morning carrying two plastic containers believed to hold flammable material, one in each hand. He was also filmed entering the Sinmyeong Building with the containers. After setting the first fire, he is believed to have walked roughly 200 meters to the Hanyang Building, set a second fire, and then fled by subway.

Police focused on the possibility of arson immediately after the fires broke out and began tracking A's movements. They determined that he had taken a taxi or walked to Dongdaemun-gu after the attacks before boarding a subway train toward Dongmyo station. Hyehwa Police Station, acting on a cooperation request from Suseo station, arrested A near Dongmyo station at around 4:16 p.m. — about four hours after the fires were set.

A had previously been detained in 2022 on charges of attempted arson after visiting the same two buildings. Police said they believe he acted out of grievances related to patent matters, given that both targeted locations housed patent law firm offices, and plan to investigate his motive further.

One person was found in cardiac arrest and 18 others were injured in Tuesday's fires. A patent attorney identified only as B was found unresponsive in a corridor on the third floor of the Sinmyeong Building and was taken to hospital. B's husband, who was also at the scene, was among the injured. Nine other people were hurt in the Sinmyeong Building fire, while about 60 evacuated on their own.

At the Hanyang Building, located about 200 meters away, eight people were injured — three with severe respiratory distress and five with minor injuries.

The injured were taken to nearby hospitals including Hanyang University Hospital, Gangnam Severance Hospital and Chung-Ang University Hospital.

Fire department crews were dispatched after receiving a report that morning that someone had set fire to the fourth floor of a building. The Hanyang Building fire was fully extinguished around 12:35 p.m., and the Sinmyeong Building fire around 2:20 p.m.