'I'll kill them all': Years-long patent grudge allegedly behind back-to-back arson attacks

What drove a back-to-back arson attack that left 19 people injured? A grudge over a paper patent certificate that had festered for years.

A man in his 70s allegedly set fire to two buildings — merely 200 meters (656 feet)  apart — housing patent firms in Yeoksam-dong, Gangnam District, southern Seoul on Tuesday. Police believe he had planned the attacks in advance as he bought plastic containers, a lighter and flammable material four days earlier. 

Police believe the suspect poured flammable material on the floor in front of an elevator of one building. He reportedly did not pour it directly on anyone. Investigators are expected to examine whether the location in front of the elevator was chosen deliberately to prevent people inside from escaping.

Police plan to seek a detention warrant for the suspect on charges of arson resulting in injury. Out of the 19 casualties, five were seriously injured and one patent attorney was found unresponsive and taken to a hospital. 

The suspect largely admitted to the attacks during questioning that started Tuesday night, police said.

Authorities are also looking into whether he intended to target a specific person. The suspect reportedly searched for a manager at one of the patent firms, but when an employee offered to find the person for him, he replied that it was “not necessary.”

“The two patent firms had scammed me by issuing false patent registration certificates,” the suspect told the police during the investigation. “I wanted to scare them and let the world know about this.”

The grievance dates back years.

The same man was sentenced to two years and six months in prison over a similar incident in December 2022 involving the same two patent firms.

At the time, he bought 2 liters (0.5 gallons) of gasoline, divided it among four plastic bottles and went to the firms. He then poured gasoline onto the employees and around the offices and threatened to set them on fire with a torch lighter, according to a district court ruling obtained by JoongAng Ilbo. He was also found to have threatened with brandished scissors while saying he would kill them.

The circumstances closely resembled the latest attacks.

The dispute began after the suspect asked the two firms in April 2019 to handle domestic and overseas design registrations and patent applications for an exercise device he had developed.

He later demanded physical paper registration certificates. Employees of the firms explained that some European countries do not issue physical certificates due to their sustainability policies.

“He came to complain four years ago too and it made no sense,” a patent attorney from one of the targeted firms said. “We explained [to him] that he could print out [the digital copy] of the confirmation certificate issued from Europe, but he kept saying he has been scammed [due to the lack of a physical paper certificate].”

The attorney said police had told him during the earlier investigation that the suspect displayed patent certificates on the wall of his home.

“I think he [set the buildings on fire] because he needed to hang up his paper certificates but couldn’t,” the attorney said. “He seemed obsessed with having a paper certificate.”

That fixation was still evident after his arrest on Tuesday.

“The patent firms scammed me,” he told reporters as he was taken into Seoul Suseo Police Station, holding up a printout of a text message.

“We should have already sent you this document,” the printouts read. “This serves as your registration certificate.”

The message is believed to have been sent by one of the patent firms after the suspect demanded a paper registration certificate.

Investigators are now looking at whether the case goes beyond arson.

Police learned that the suspect allegedly told a neighbor something to the effect of “I’ll kill them all” as he left home carrying containers of thinner or another flammable substance.

Under the Korean law, attempted murder charges could apply if investigators determine that he knowingly set the fires despite being aware that people could die.

BY HEO JEONG-WON, NOH YU-RIM, KIM JI-HYE [[email protected]]