The man accused of fatally stabbing 19 people and injuring 20 more in an attack at a home for the disabled may have forecast the massacre in a rambling letter that was given to police in mid-February.
Satoshi Uematsu, 26, who surrendered at a local police station after Tuesday's attack, was a former employee of the facility but had resigned earlier this year after a falling out with the management.
His behavior at the time was considered disturbing enough that he was held for several days for a psychiatric evaluation before authorities concluded he no longer posed a risk, and released him.
After the violent attack in the city of Sagamihara — just outside Tokyo — some wondered whether authorities had failed to recognize the warning signs that the former nursing home caretaker was erratic and potentially violent. In the letter, he hinted broadly at a possible attack and said he believed that disabled people were a burden on society.
Yuji Kuroiwa, the governor of Kanagawa prefecture, publicly apologized after the attack for failing to take better preventative steps.
Even against the backdrop of horrific global violence in recent months, the attack in Japan was jarring. Such attacks here are rare, and the massacre at the nursing facility is reportedly the island's largest mass slaying by a lone killer since World War II.
According to Jiji Press, Uematsu starting working as a caretaker at the nursing home, Tsukui Yamayuri-en, in 2012.
"He was a normal person back then but one day suddenly he started displaying discriminatory behavior towards the disabled," the facility's director said.
A neighbor, 73-year old Akihiro Hasegawa, recalled Uematsu as "a nice and polite person" who frequently entertained guests and could be heard laughing with friends.
But his behavior seemed to veer in another direction on Valentine's Day, when he attempted to deliver a three-page letter to Japan Parliament Lower House Speaker Tadamori Oshima's residence in Chiyoda-ku, Tokyo. The letter reportedly described his wishes for Japan to legalize euthanasia for disabled people. It also included his name and address.
The hand-written letter, which was obtained and released by the Mainichi newspaper, begins abruptly, with the writer saying he "is able to kill 470 disabled people" and a disclaimer that he realizes his threats defy common sense. Uematsu said he reached the conclusion that his plan to kill the disabled should be put "into action" and that "looking at the exhausted faces of the caretakers and the lifeless eyes of the employees of the caretaking facilities makes me feel for Japan and the world."
The disabled, he wrote, "live as animals, not humans and many must succumb to a wheelchair for life while often being shunned from their own families."
He said his goal was a world "where the severely disabled who cannot manage life at home or be an active member of the society can make the choice of being euthanized with the consent of their guardians. The disabled are only capable of creating unhappiness."
The letter rambles in part, touching upon his training to become a teacher, his experience in the transportation business and two encounters with a UFO. He also writes about gambling, the Freemasons and his belief that marijuana should be legalized.
According to published reports, Uematsu also detailed plans to target his former workplace.
"I will strike at night when there are fewer staff on call," he wrote.
He concludes with demands that the Japanese government reward him for his actions.
"After my arrest, I wish to be held no longer than two years and to live a free life thereafter. Not guilty by reason of insanity. New name, family registration, all documents necessary to continue life such as a driver's license and plastic surgery as a means to participate in the mimicry to society. 5 million yen in financial support. I demand a commitment to the above. As soon as your decision is made, I am ready to put my plans into action…. Please take it up with Prime Minister [Shinzo] Abe."
Initially, Uematsu's letter was not accepted, so the caretaker returned the next day and persisted until an officer on patrol accepted it.
A spokesman for the Secretary Department of the Lower House Office of the Parliament recounted that after receiving the letter, said the department contacted the Tokyo Metropolitan Police, which in turn handed it over to the Kanagawa Prefectural Police.
Uematsu ultimately was deemed to be "potentially harmful to others" and he was held for psychiatric evaluation, according to reports. Marijuana was detected in his system and, 12 days later, he was released after it was determined he was "no longer a danger to others."
"I have resigned from the company. I may even be arrested…," he tweeted the day he was hospitalized.
Active on social media, Uematsu posted tweets ranging from the banal to the disturbing. In early 2015, he posted a picture of his tattooed back and buttocks noting, "The company found out! I think I'll just ride it out with a smile on my face. I'm 25 and I'll do my best." He also expresses concerns about AIDS and radiation and expressed delight that the augmented reality game Pokemon Go is a huge hit.
His final tweet was at 2:50 a.m., after the nursing facility attack but before he surrendered. He writes in Japanese that "may the world become peaceful" and adds in English: "beautiful Japan!!!"
He is wearing a suit in the photo, and smiling.
Adelstein is a special correspondent
Correspondent Mari Yamamoto contributed to this report
12:55 p.m.: This article has been updated with Times reporting.