The suspect in a knifing rampage that left seven dead in Tokyo was handed over to prosecutors Tuesday, as media reports pulling together Internet postings and police statements drew a picture of an angry, lonely young man who meticulously planned the deadly attack.
Tomohiro Kato, a 25-year-old factory worker, was transferred from police custody to that of the Tokyo prosecutors' office for further questioning into Sunday's attack, in which he allegedly slammed a rented truck into a crowd of pedestrians, then jumped out and began a stabbing spree.
A police spokesman who requested anonymity because the investigation is ongoing said Kato has at times broken down in tears during questioning. He said the suspect has been unapologetic but otherwise cooperative. He refused to give further details.
Police also conducted a search of Kato's apartment Tuesday and confiscated empty packages that had contained knives. They also found receipts for the weapons and at least one club, a separate spokesman said, under the same condition of anonymity.
Three people were killed by the impact of the truck and four others died of stab wounds, police said. Another 10 were injured. Kato, blood spattered on his face and clothes, was arrested on the spot. It was the worst murder rampage in Tokyo in recent memory.
According to several Japanese media reports, Kato told police that he went to Akihabara the day before the rampage to plan his assault and sell his home computer to raise money to rent the truck. The popular shopping district is a hangout for young people and a center of Japan's comic book and computer game culture.
Police refused to confirm those reports.
Though the motive for the crime remained a mystery, more details came out in the media Tuesday about Kato's background and his metamorphosis from award-winning tennis player in high school to secluded and virtually friendless temporary worker in a factory outside Tokyo.
Three days before the attack, Kato lost his temper at the auto parts factory where he worked in Shizuoka, about 100 miles (160 kilometers) southwest of Tokyo, said company executive Osamu Namai.
"He was screaming that his uniform was missing. When his colleague got a new uniform for him, he had already left and never returned," Namai told reporters. Namai, however, added that Kato was a "very serious" worker and had not stood out as a troublemaker.
Public broadcaster NHK reported that Kato bought a knife with a 5-inch (13-centimeter) blade at a camping and outdoor supply shop two days before the attack. A surveillance video showed him laughing with the shopkeeper and at times making stabbing motions with his hands.
In the days leading up to the attack, Kato also sent a slew of postings from his mobile phone to an Internet bulletin board, police said.
The suspect was believed to be posting messages on a site called the "Extreme Exchange," one of what experts see as a growing number of sites used by people looking for accomplices in criminal activities, someone willing to join in group suicides or sellers and buyers of illegal drugs.
Access to the site has been halted.
Though officials refused to comment further, Japanese media said the postings showed a very disturbed man raging against society and vowing to get revenge by unleashing his fury on the streets of Akihabara. The main street in Akihabara is closed to traffic on Sundays, allowing large crowds of pedestrians to flow into the area.
A chronicle of Kato's messages, carried by The Asahi, a major newspaper, portrayed a man at breaking point:
"Oh, I am hopeless," he reportedly wrote two days before the attack. "What I want to do: commit murder. My dream: to monopolize the tabloid TV shows. ... I saw a loving couple at a river bank. I wish they were killed by (being) swept away by the river."
"Since I was young, I was forced to play a 'good boy,"' he wrote the next day. "I'm used to deceiving people."
Just 20 minutes before the attack, he posted his last message: "It's time."
The National Police Agency on Monday requested an association of Internet providers to immediately report any site containing messages hinting at a crime.
Tokyo Metropolitan Police also warned Tuesday that one of the slashing victims had hepatitis B, and issued a public notice urging anyone who might have come into contact with blood from the rampage to come forward for a medical check.
No charges have been filed against Kato.
Under Japanese law, a suspect can be held by police for two days and then must be transferred to the custody of prosecutors, who have 20 days to either file charges or release the suspect.