A Japanese court on Thursday sentenced a 45-year-old man to death for setting fire to the renowned Kyoto Animation studio in 2019, which left 36 people dead in the country’s worst mass killing in almost 20 years, according to public broadcaster NHK.

The defendant, Shinji Aoba, was charged with murder and arson after telling police his work had been plagiarized and that he used gasoline to set fire to the studio. He was found guilty by the Kyoto District Court on Thursday.

Dozens of people were inside the three-story building at the time of the blaze, which spread so rapidly that many did not have time to escape, police said at the time. All those who died were employees, with at least 32 others injured.

In his ruling, the court’s presiding Judge Keisuke Masuda called Aoba’s crime “truly atrocious and inhumane.” The victims’ deaths were “too serious and tragic,” Masuda said, describing how flames and smoke engulfed the studio.

“The horror and pain of the victims who died in Studio 1, which turned into a hell in an instant, or who died afterward, is beyond description,” the judge said.

In a 2019 news conference, police said Aoba had unspecified mental health issues.

He pleaded not guilty at the trial, which began last September, with his defense lawyers arguing he had a mental disorder and could not be held criminally responsible.

Prosecutors however called for the death penalty, arguing Aoba was fully competent.

Among industrialized democracies, only Japan and parts of the United States retain capital punishment. Rights group including Amnesty International say international law prohibits using the death penalty against people with mental disabilities.

On Thursday, the judge ruled that Aoba could determine right and wrong at the time of the incident, according to NHK. His capacity for responsibility was “determined to have been neither insane nor mentally incompetent at the time of the crime,” NHK reported.

The fire marked the worst mass killing in Japan since a 2001 arson attack on a building in Tokyo’s Kabukicho district, which killed 44 people. The death toll also surpassed the infamous Tokyo sarin gas attack on a subway in 1995, which killed 13.

The Kyoto attack left fans worldwide grieving the loss of life and a studio that claimed to put its employees first and was a major force in the industry.

Founded in 1981, Kyoto Animation – known as KyoAni – made its name producing high quality animations that draw on both the mystical and the mundane.

Its popular works include animated series “Free!,” manga series “K-On!,” the anime TV adaptation of “the Melancholy of Haruhi Suzumiya” and “Violet Evergarden,” which Netflix picked up in 2018.

This story has been updated.