The man believed to have set one of Japan’s most popular animation studios ablaze, killing 33 people, told authorities he started the fire on Thursday because he believed the studio had plagiarized his novel. The suspect has been identified by Japanese public broadcaster NHK as Shinji Aoba, a 41-year-old who reportedly served time for robbing a convenience store in 2012 and received care for mental illness. “I did it,” Aoba is said to have told the arresting officers, though police have been unable to question him because he was being treated for burns. Many employees told officials that Aoba had no professional connections to Kyoto Animation. Ten employees remain in critical condition. Twenty of the victims were women, according to The New York Times, as Kyoto Animation was known for hiring more women than other studios. Reuters reports most of the bodies were found piled on a staircase leading up to the roof, but firefighters later found that exit door was closed. The building’s three-story spiral staircase amplified the effects of the fire, acting like a chimney, Tokyo architect Momoko Higuchi told Reuters. "Because the fire was with petrol, the effect was like a bomb," he said.