Police sent prosecutors investigative papers Friday on eight current and one retired police officer in central Japan in connection with alleged inappropriate treatment that led to the death of a detained man suffering from chronic diseases late last year.

The allegations they face include professional negligence resulting in the death of the 43-year-old man who was being held in a cell at the Okazaki police station in Aichi Prefecture. The man was battling schizophrenia and diabetes and died of kidney failure but is suspected of not receiving adequate medical care.

The Aichi prefectural police apologized at a press conference for causing the "grave consequence" and offered condolences to the man's family. A total of 27 people were punished over the case.

Shinji Hiramatsu, head of police administration at the Aichi prefectural police, bows in apology at a press conference in Nagoya, central Japan, on Dec. 1, 2023. (Kyodo)

Okazaki police station chief Hiroshi Shimazaki escaped criminal liability but resigned Friday. The prefectural police penalized the 60-year-old with a three-month pay cut for not making rounds to the holding cells the entire time the man was detained.

The man was arrested on Nov. 25 last year for allegedly obstructing official duties and died on Dec. 4. He was also showing symptoms of dehydration.

According to police investigations, the man had been placed in solitary confinement as a result of violent behavior. Restraining devices, such as handcuffs and ropes, were used on him for a total of 144 hours.

He was not given access to medicine for his chronic illnesses nor provided medical assistance even though he was refusing meals.

Security camera footage also showed the man apparently being kicked, and the case was referred to prosecutors for assault by police officials.

The prefectural police believe the assault is unlikely to have any causal connection to the man's death.

The 72-year-old father of the man has expressed intense anger against the police, saying that his son was not treated like a human being.

The father said his son remained in detention even after he explained to police about his schizophrenia and that he needed to be hospitalized. The father also questioned the decision by police to use restraining devices when it was clear that his son's violent behavior was linked to his illness.

In the wake of the incident, the National Police Agency decided to impose stricter rules on the use of instruments of restraint on detainees at local police stations, including getting permission from prefectural police headquarters and limiting the time one can be restrained by handcuffs and ropes to no more than 3 hours.

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