The suspect in a fatal fire at a mental health clinic in Osaka last week may have intended to copy a deadly 2019 arson attack on an animation studio in Kyoto, which also involved the purchase of gasoline ahead of time, investigative sources said Tuesday.

Discovered in the house where Morio Tanimoto, 61, was believed to be living in Osaka's Nishiyodogawa Ward was a newspaper article about the animation studio fire that claimed 36 lives, prompting police to believe he might have decided to use a similar method, the sources said.

Flowers are placed on Dec. 20, 2021, in front of a multiple tenant building recently hit by a deadly fire in Osaka. A 61-year-old male patient of a mental clinic in the building is suspected of starting the fire on Dec. 17 that killed 24 people. (Kyodo) ==Kyodo

The death toll from the Osaka clinic fire on Friday increased to 25 after a woman apparently in her 20s was confirmed dead early Tuesday morning, the police said. After the fire, 27 people were taken to hospitals including Tanimoto, who remains in serious condition due to carbon monoxide poisoning.

Of the 25 victims, 21 have been identified including the clinic's director, Kotaro Nishizawa, 49, the police said.

According to the sources, a small fire broke out in Tanimoto's living quarters about 30 minutes before the clinic fire, with police suspecting he may have tried to ignite some gasoline ahead of the planned arson attack.

Photo taken Dec. 20, 2021, shows flowers placed in front of a multiple tenant building recently hit by a deadly fire in Osaka. A 61-year-old male patient of a mental clinic in the building is suspected of starting the fire on Dec. 17 that killed 24 people. (Kyodo) ==Kyodo

It was found that Tanimoto, a patient at the clinic, purchased around 10 liters of gasoline in late November, apparently claiming it was for his motorcycle. The finding led police to think he had a strong intent to kill people, the sources said.

Footage of security cameras installed at the clinic showed the suspect placing a paper bag in front of the reception area. He then crouched by the bag and moved his hand, following which fire was seen quickly rising to the ceiling.

A burned cigarette lighter was found where the fire is thought to have started. The footage also showed the suspect trying to grab people as they attempted to flee the fire, according to the sources.

Tanimoto is also believed to have attempted to seal the clinic's emergency exit with adhesive tape from the outside a day before the fire to prevent people from escaping, other investigative sources said.

Nishizawa told his wife he had discovered tape on the door leading to the fire escape the day before the incident and removed it, according to the sources.

While the motive for the attack remains unclear, testimonies of people who know Tanimoto and his employment history suggest he lived a lonely life after going through a divorce and the deaths of family members, and he had suicidal thoughts.

The suspect's older brother said he has not had contact with him for more than 30 years, adding their father died around 30 years ago, while their mother died some 10 years earlier than that.

The president of an Osaka sheet metal factory where Tanimoto used to work said the man often complained about his marriage from around 2008, when he briefly left the company and got divorced.

His former wife did not accept efforts to reconcile after the divorce, and an attempt of a second marriage to another woman also failed.

Acknowledging that Tanimoto had been a diligent worker, the former employer, 78, also said, "I never heard of him having friends or acquaintances, and he had no relationships with other employees outside of work."

Tanimoto also attempted to murder his eldest son in April 2011 and the Osaka District Court later sentenced him to four years in prison over the case.

The ruling said the accused "could not bear the loneliness after the divorce and wanted to die but was too afraid to commit suicide. He thought of killing other people so he could then bring himself to end his own life."

His lawyers had sought a suspended sentence, arguing it was possible he was affected by mental illness.

However, the Osaka court rejected the claim, saying rehabilitation was possible if he had relationships with people other than his family.

"I think he tried to die for sure this time by setting a fire," said Noboru Aitani, a professor of criminal psychology at Kansai University of Welfare Sciences. "I also think this (incident) is connected to his failure to commit murder-suicide 10 years ago."

Mafumi Usui, a professor of social psychology at Niigata Seiryo University, said, "To prevent similar crimes, it is important to find out what the suspect was thinking following the Osaka court ruling and what triggered the arson this time."