The suspect in a shooting and stabbing attack in central Japan's Nagano Prefecture that resulted in a 12-hour standoff and left four people dead was referred to prosecutors Saturday.

Masanori Aoki, 31, had been arrested on suspicion of the murder of one policeman, who was killed along with another police officer who rushed to the scene in the city of Nakano, following a standoff at his home. The other fatalities were two local women whom he believed "said bad things about me," according to police.

He was also quoted as telling the police that he killed the policemen over fears they would "shoot and kill me."

A car carrying Masanori Aoki, who was arrested in a stabbing and shooting attack in Nagano Prefecture, central Japan, leaves the Nagano Central Police Station on May 27, 2023. (Kyodo)

Aoki, the son of a local assembly member who has since resigned, holed up for around 12 hours from the night of Thursday into the early hours of Friday morning after the attacks.

Investigative sources said they eventually convinced him to give up after numerous phone calls. The police also said he had appeared to be considering suicide during the siege.

According to the police, Aoki is believed to have stabbed Yukie Murakami, 66, and Yasuko Takeuchi, 70, who would often go out walking together.

He then fired at the two policemen -- Yoshiki Tamai, 46, and Takuo Ikeuchi, 61 -- who arrived at the scene before barricading himself in the house.

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