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 during the rampage, and his motives for the horrifying assault remain unclear.
On Wednesday morning, police searched his 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 80s, but gave no further details.
Police had no comment on the investigation and declined to offer any further details 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 parent, identified as government official Satoshi Oyama, a Myanmar specialist.
Seventeen more people, mainly young children, were injured, according to authorities.
Iwasaki crept silently up behind pupils of the Caritas Gakuen (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.
But by Wednesday morning, few details had emerged about the attackers and his motive for the assault, with neighbours telling local media that they knew little about the man.
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 gone to local schools, but there was no confirmation.
A man who identified himself as having taught Iwasaki in junior high school, when the suspect was around 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 take public transport alone to get to and from school.
"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 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.
The Caritas school will be closed for the rest of the week, and officials said on Tuesday that they would offer students mental health support after the attack.