Japanese police on Wednesday searched the home of the man behind a stabbing rampage in the town of Kawasaki a day earlier that killed two people, including a child.
The 51-year-old attacker, identified by police as Ryuichi Iwasaki, died after stabbing himself at the scene.
His motive for the horrifying assault remains unclear.
On Wednesday morning, police searched Iwasaki’s home, not far from the scene of the morning attack, seizing unspecified material, public broadcaster NHK reported.
Local media said Iwasaki was living with relatives in their eighties, but gave no further details.
Police had no comment on the investigation and declined to release more information about the attacker.
The rampage in the town south of Tokyo on Tuesday morning killed two people – 11-year-old schoolgirl Hanako Kuribayashi and a 39-year-old father, who was identified as government official Satoshi Oyama, a Myanmar specialist.
Seventeen more people, mainly young children, were injured, authorities said.
Iwasaki crept silently up behind pupils of Caritas Elementary School as they waited for their school bus and began slashing randomly at them armed with knives in both hands, before fatally stabbing himself in the neck.
Even on Wednesday morning, few details had emerged about the attacker or his motive for the assault, with neighbours telling local media that they knew little about him.
A female neighbour told Kyodo news agency that Iwasaki had said good morning to her 40 minutes before carrying out the attack, an interaction she described as unusual.
The news agency said Iwasaki was believed to have attended local schools, but this was not confirmed.
A man who identified himself as having taught Iwasaki in junior high school, when the suspect was aged about 14, told NHK he was “not the kind of child who stands out”.
“He and his friends would shove each other playfully, but he didn’t attack anyone violently,” the teacher said.
In the wake of the attack, Japan’s government said it would review measures to ensure the safety of children travelling to and from school.
Japan has one of the lowest rates of violent crime in the developed world, and it is common for even young children to use public transport alone.
“The whole government will work in unison to ensure the children’s safety,” government spokesman Yoshihide Suga told reporters after a ministerial meeting on the issue.
The attack has shocked Japan, where violent crime is vanishingly rare, in part because of strict regulations on gun ownership.
On Wednesday morning, people were still arriving at the scene of the attack to lay flowers and other tributes to those killed.
Caritas school will be closed for the rest of the week, and officials said on Tuesday that pupils would be offered mental health support.