Osaka police turned over to prosecutors Friday cases against nine of their own, including former superintendents, in connection with the falsification of investigation records for a 41-year-old man taken into custody last year.

The man in custody had allegedly become violent with police and was placed in a solitary cell, a move that required the authorization of a superior who was not present at the time. The authorization was fabricated.

Kiyoshi Nakai, 59, a senior superintendent in charge of the Sakai Police Station, and Superintendent Masaki Furukawa, 60, his second in command, are alleged to have knowingly submitted falsified reports to prosecutors in connection with the incident.

The prefectural police also punished 11 other officers, including Shinichiro Kuwahara, 51, who headed the criminal investigation bureau as a chief superintendent, for failing to prevent the coverup, bringing the total number of those punished to 20.

The scandal involved an unusually large number of officers, according to the National Police Agency.

But the Osaka police denied there had been an organized conspiracy and claimed that Kuwahara and other ranking officers who signed off on the false reports merely failed to detect the wrongdoing because they had not been sufficiently briefed by underlings.

Nakai and Furukawa have admitted to the charge by saying they intended to wait for an instruction from headquarters in keeping the false records in the station.

They are among four people who have since voluntarily left the force.

The seven others whose cases were sent to prosecutors without arrest were assigned to the station at the time and are suspected of involvement in falsifying the records.

The police are seeking indictments for three of them, including a 51-year-old assistant inspector who is believed to have prompted others to falsify the records.