A man who had publicly advocated for involuntary euthanasia is alleged to have carried out an attack on a home for the disabled in Japan Tuesday, killing 19 people.

Satoshi Uematsu, 26, was quoted as saying, “It is better that disabled people disappear,” when he turned himself in at a local police station after the attack at the Tsukui Lily Garden in Sagamihara, south of Tokyo, according to The Guardian.

Uematsu was carrying a bag full of knives and other sharp-edged tools, some of which were bloodstained, when he handed himself in. He is a former employee of the Tsukui Lily Garden.

Nine women and 10 men were killed, the fire department was quoted as saying, and they ranged in age from 18 to 70. It was the country’s worst mass killing in decades.

Authorities said Uematsu had been “involuntarily committed” to hospital on Feb. 19, after police in the town of Tsukui contacted him in response to a letter he had attempted to pass to the speaker of the lower house of Japan’s parliament, The Guardian said.

In the letter, Uematsu argued that the government should permit euthanasia for disabled people, said he would be willing to carry out such killings himself, and detailed how he would do it. “I envision a world where a person with multiple disabilities can be euthanised, with an agreement from the guardians, when it is difficult for the person to carry out household and social activities,” the letter said. Uematsu’s letter said he could “wipe out a total of 470 disabled individuals” by targeting two facilities for disabled people during the night shift, “when staffing is low.” “The act will be carried out speedily, and definitely without harming the staff. After wiping out the 260 people in two facilities, I will turn myself in.” He was released from hospital on 2 March. … The Tsukui Yamayuri-En facility is situated in three hectares (7.6 acres) of grounds. Established by the local government and located on the banks of the Sagami river, it cares for people with a wide range of disabilities.

Pope Francis sent a message of condolence to the archbishop of Tokyo. As the Vatican’s news service reported: