Tokyo -- Police were investigating Friday the gutted animation studio building in Kyoto where a man raging about theft set a fire that killed 33 people, crushing the hearts of comic fans in Japan and beyond. Witness accounts and reports suggested the man had a grudge against Kyoto Animation, but police only have said the suspect, who is still hospitalized, is a 41-year-old man from near Tokyo who did not work for the studio.

Later Friday, Kyoto police identified the man as Shinji Aoba, according to the Japanese broadcaster NHK and other media. The reports, quoting an unnamed source, said Aoba spent three and half years in prison for robbing a convenience store in 2012 and also had mental problems. Police would not immediately confirm the reports.

The man told police that he set the fire because he thought "(Kyoto Animation) stole novels," according to Japanese media. It was unclear if he had contacted the studio earlier.

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The company founded in 1981 and better known as KyoAni made a mega-hit anime series about high school girls and trained aspirants to the craft.

The shocking attack left another 36 people injured, some critically. It drew an outpouring of grief for the dead and injured, most of them workers at the studio.

Construction worker Takumi Yoshida, 23, was a fan. "I am shocked and I'm sure for their families it must be very difficult. So with those feelings in my mind, I brought flowers," Yoshida said.

Anime fan and university student Yuki Seki traveled from nearby Hyogo prefecture to pay her respects. "After properly recovering while taking their time, I hope Kyoto Animation can once again share their power and energy with us," she said.

About 70 people were working inside the 3-story Kyoto Animation No. 1 studio in southern Kyoto, Japan's ancient capital, Thursday at the time of the attack.

The arsonist arrived carrying two containers of flammable liquid. He shouted, "You die!" as he entered the studio's unlocked front door, dumped the liquid and set it afire with a lighter, according to officials and media reports. Police at the scene confiscated the gasoline tanks, a knapsack and knives, but have not confirmed they belonged to the attacker.

An expert interviewed by CBS News partner network TBS TV said the compactness of the approximately 7,500-sq. foot structure and the fact that there was only one exit made it especially vulnerable to an attack on the building's entrance. The perpetrator apparently went to great lengths to plan the crime and obtain gasoline, the sale of which is tightly controlled in Japan; it is not sold in containers.

The blaze blocked the front door and quickly engulfed the workspace, rising up the stairs to the third floor, sending panicked employees fleeing. Some were able to escape by crawling out of windows. Many tried but failed to escape to the roof, the reports said.

The suspect fled but was chased by studio employees who eventually caught him. He collapsed to the ground outside a house and was quickly surrounded by police.

"They are always stealing. It's their fault," he told policemen bending over and asking him why he set the fire, according to a witness who described the scene outside her house. The man complained bitterly that something had been stolen from him, the witness told NHK and other networks.

Neighbors interviewed by NHK said the suspect had troubles with neighbors at the apartment building in Saitama, north of Tokyo, where he lived.

One man told the broadcaster TBS that he had knocked on Aoba's door to ask him to stop banging on the walls. He said Aoba shouted "I will kill you!" and grabbed him by the hair and shirt.

Kyoto Animation's hits include "Lucky Star" of 2008, "K-On!" in 2011 and "Haruhi Suzumiya" in 2009. It has an upcoming feature film, "Violet Evergarden," about a woman who professionally writes letters for clients.

It's also done secondary animation work on a 1998 "Pokemon" feature that appeared in U.S. theaters and a "Winnie the Pooh" video.