The suspect in last week's shooting and stabbing attacks in central Japan that left four people dead asked his mother to shoot him during an hours-long standoff at his home, an investigative source said Monday.

Masanori Aoki, 31, surrendered to police after holing up for about 12 hours following the attacks on Thursday afternoon, and was arrested for the alleged fatal shooting of a policeman with a hunting rifle.

During the standoff, Aoki, the son of a local assembly member who resigned following the incident, contemplated suicide but could not go through with it, so he handed a gun to his mother and asked her to shoot him, the source said, citing the account the mother gave to the police.

Police officers remain on alert in Nakano, Nagano Prefecture, on May 29, 2023, following the previous week's shooting and stabbing attacks there that left four people dead. (Kyodo)

The mother took the gun, ran away and placed it on a road near the home in Nakano, Nagano Prefecture.

According to the police, the suspect has held and renewed licenses for four hunting guns, including shotguns and air guns, since 2015. One of them may have been used in the slayings.

Aoki is believed to have first stabbed two local women and returned to his home nearby before going out again with a hunting gun.

He allegedly fired at the driver's side of a police car that arrived following a report about a stabbing, resulting in the deaths of the two policemen -- Yoshiki Tamai, 46, and Takuo Ikeuchi, 61. Aoki then barricaded himself in his home.

One of the stabbing victims, Yasuko Takeuchi, 70, was found collapsed around 50 meters from Aoki's home, while the other, Yukie Murakami, 66, who is believed to have been taking a walk with Takeuchi and tried to run away from Aoki, was stabbed from behind, the source said.

Aoki has been quoted as telling investigators that the women said "bad things about me."

After a 12-hour standoff, Aoki was eventually persuaded by the police and his father to give himself up and came out of the house in the early hours of Friday.

Aoki was quoted as telling investigators that he killed the policemen as he was afraid they would "shoot and kill me."

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