At about 2:30 Tuesday morning, a man broke into a care facility for the mentally disabled in the city of Sagamihara, 50 kilometers southwest of Tokyo. After tying up nightshift workers, he began a stabbing rampage against the home's residents. Nineteen people were killed - 10 women and nine men aged between 19 to 70. Another 25 were injured, many of them seriously with stab wounds.

"These people were sleeping and were seriously disabled, which made it possible for him to kill so many," one resident said on television.

Following the massacre, the attacker, dressed fully in black, drove his own car to the nearest police station. He arrived at about 3 a.m. with the words "I did it." He presented a bag with three blood-smeared knives, among other tools. The man, identified by police as 26-year-old Satoshi Uematsu, justified his rampage by saying that it would be better if there were no handicapped people. Cabinet speaker Yoshihide Suga ruled out any terrorist connection.

The attack was the biggest massacre in Japan since the end of World War II, and it has shocked the population. Homicides are rare in Japan - only 0.3 murders occur per every 100,000 people, one of the lowest rates in the world. The use of firearms is forbidden, as is carrying a knife with a blade longer than nine centimeters in public. Only a few people were killed in 2015 from gunshot wounds.

The last mass killing in Japan took place in 2008, when a man drove a truck into a crowd in Tokyo and set upon it with a knife. Seven people were killed and a further ten were injured.

A plan revealed in advance

After completing his studies, the Sagamihara attacker worked at the home, named Yamayuri En (Mountain Lily Garden) and run by regional authorities, as a caregiver from December 2012 until this February, when he quit for "personal reasons."

Uematsu originally wanted to become a teacher and took an aptitude test for the profession. According to Japanese media reports, friends and neighbors described him as a "cheerful" person that liked attending parties. But his work at the home seems to have changed him.

After quitting, he wrote a letter to the speaker of parliament and delivered it personally to his home. In it, he described in detail his planned massacre, faithfully executed months later: He wrote that he was going to break in at night into the home and kill its residents. Afterwards he would turn himself in to the police.

"I dream of a world in which the handicapped can die in peace," he wrote. He bemoaned that these people often sat their entire lives in wheelchairs, without contact to their family members.

Removed from society

Uematsu was arrested shortly thereafter and questioned by the police. Seen to be a danger to the community, he was admitted on February 19 to a psychiatric hospital. Blood tests showed marijuana use. But he was released on March 2. The doctors believed that his condition had improved.

Yuji Kuroiwa, governor of the prefecture of Kanagawa, where the home is located, offered an apology to the victims and their families. He said they would be supported and the home's security measures would be improved.

Kuroiwa avoided drawing any political conclusions, as is usual in Japan in the aftermath of such occurrences. But there had recently been a debate about the poor level of care in homes for the elderly and orphans. The mentally disabled are rarely in the public view in Japan. They are often kept at home by their closest of kin or housed in closed-off care facilities.