TOKYO – He wrote that he intended to kill disabled people and that his plot would benefit Japanese society. The facility where he worked was so unnerved, it confronted him. He quit the job and police sent him to a psychiatric hospital, but doctors deemed him safe to release 12 days later. In the months that followed, his former workplace increased security, adding cameras to watch the buildings where 150 mentally disabled people resided. But he was left alone, free, unmonitored.
In the early morning darkness, Satoshi Uematsu entered the Yamayuri-en facility and killed or injured nearly a third of its patients within 40 minutes, Kanagawa prefectural authorities said. He turned himself in Tuesday morning about two hours after Japan's deadliest mass attack in the post-World War II era.
Uematsu, 26, was known to his neighbors as a pleasant young fellow but is now seen as a monster grinning inside a police vehicle taking him to a district prosecutors' office Wednesday for questioning.
The first apparent concerns were raised this year. After he was released in March from the psychiatric ward where he had been committed, he was free. His release was legally approved by Sagamihara, the city outside Tokyo where he lived and had worked. He was supposed to live with his parents for monitoring at a designated address, officials said, but that did not happen.
"Information of his release from the hospital wasn't fully shared among the authorities," said Yuji Kuroiwa, governor of Kanagawa prefecture. "We need to examine how that happened."
The first concern about Uematsu was raised in January when his colleagues spotted his tattoos, which in Japan are widely linked to yakuza crime syndicates. Yamayuri-en executives in early February made sure he hid them at work, said Katsuhiko Yoneyama, head of an organization that runs the facility.
Officials also learned that Uematsu started telling his colleagues that disabled people should be all put to death, Kaoru Irikura, head of Yamayuri-en facility, told reporters Wednesday. Irikura also recalled a report of Uematsu scribbling on patients' hands, citing it as earlier sign of his "lack of respect" to the disabled.
In mid-February, Uematsu also visited Parliament. He delivered a letter to the lower house speaker expressing his ideas about killing the disabled. He sat outside the house speaker's official residence for two hours, until an official took the letter.
Uematsu boasted in the letter that he had the ability to kill 470 disabled people in what he called "a revolution," and outlined an attack on two facilities, after which he said he would turn himself in.
Authorities acted promptly. Within hours, parliamentary security officials submitted the letter to the Tokyo police because of its "criminal threat." Tokyo police notified the police in the town Uematsu lived, and they called the Yamayuri-en facility two days later.
At the Feb. 19 meeting with Uematsu, the facility's executives confronted him over remarks and the letter. Uematsu insisted that he was not wrong and quit the job. Later that day he was sent by police to a facility giving him psychiatric treatment.
Uematsu was diagnosed as having mental conditions that could be harmful to society requiring an emergency hospitalization. He also tested positive for marijuana, and another assessment three days later showed his mental condition hadn't improved. But only nine days later, the doctors decided his symptoms had ended and he could go home.
He returned home, even though his parents had moved out, according to his neighbors, and he was therefore not able to meet the requirements of his release. A city official in charge of mental health said his release was legally approved and there was nothing more they could do because continuing monitoring was tantamount to a human rights violation and unethical. The official requested anonymity because of sensitivity of the issue.
Experts say there could have been instances where officials could have prevented the disaster, if authorities had used more caution.
"It would be desirable to establish a system that provides certain levels of monitoring, but that also creates the issue of privacy and prejudice," Yasuhiro Yuki, a social welfare expert at Shukutoku University, told a TBS television talk show. "We need to balance human rights and monitoring."
At the Yamayuri-en, officials had been uneasy since Uematsu left. At the recommendation of local police, the facility installed 16 security cameras in March at the complex where the about 150 patients lived in four two-story buildings, each with automatic door locks.
They added security guards during an event in June when outside guests visited the facility.
But overall security at the facility was perhaps not enough. Kanagawa prefecture welfare department official Shogo Nakayama said that the only security guard on night duty was allowed to sleep, and there were only eight other caregivers, one on each floor.
But Nakayama acknowledged the need to reconsider security at the facility and staff qualifications.
"We do have to learn the lesson from what happened," he said.
Follow Mari Yamaguchi on twitter https://www.twitter.com/mariyamaguchi
Find her work also at http://bigstory.ap.org/content/mari-yamaguchi