A 53-year-old man suspected of abandoning the body of a female university student in his apartment in Sapporo, Hokkaido, has told police she asked him to kill her, investigative sources said Thursday.

Hokkaido police have been questioning Isamu Ono after the body of 22-year-old Yuina Segawa was found in his apartment on Saturday.

A police officer stands guard near the home of Isamu Ono on Oct. 10, 2020, in Sapporo, northern Japan. (Kyodo)

The woman left her home in Otaru, Hokkaido on Oct. 3 after telling her family she was going to meet a friend. Her family lost contact with her and reported her missing on Friday. Security camera footage and Segawa's smartphone signal eventually led investigators to an area near the suspect's residence.

An autopsy has suggested Segawa died around Oct. 4 and that she was suffocated.

A post made on Oct. 6 on what the police believe is Ono's Twitter account said, "I will do what I can for the repose of her soul," according to the sources. Among other tweets on the same account, one posted on Saturday said, "A person I became acquainted with on Twitter died in accordance with her wish."

Surveillance camera footage taken on Oct. 3 from a train station in Sapporo at around 11 a.m. captured a woman believed to be Segawa in the passenger seat of a black rental car driven by a man suspected to be Ono, the sources said.

A different Twitter post believed to be made by Ono referred to a black rental car and meeting a friend for a meal and shopping, according to the sources.

Ono was described as telling police that the pair had first got to know each other online, and that they had met in person previously.

Segawa's body was found at his residence when investigators conducted a search on suspicion of unlawful confinement. He was initially apprehended outside his home on the same day for carrying a knife, according to the police.

People who know Ono said he had claimed to have experience in the Self-Defense Forces and as a taxi driver. He is currently unemployed, the police said.

Acquaintances said he appeared to develop severe mental health problems some years ago which led to him quitting his job. He has previously posted images of the sleeping medication and antidepressants he uses, and had also written questioning the value of being alive.

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