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 had schizophrenia and diabetes and died of kidney failure. He is suspected of not receiving adequate medical care.

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