The knife-wielding attacker who slit the throats of dozens of residents at a care home for people with disabilities on Tuesday cited a belief in the ideology of Nazi leader Adolf Hitler during a brief period of hospitalization in February. He was so persistent in his threats that the facility installed extra security and kept in close contact with police.

A disabled people's lobby group has said the slaughter by suspect Satoshi Uematsu, 26, smacked of eugenics and came amid a background of hate speech, including against people with disabilities. The Japan National Assembly of Disabled Peoples' International said Japan needs to do more to create a fully inclusive society.

The slew of warning signs led some to question whether officials should have done more to prevent the attack.