HALIFAX -- A Nova Scotia agency that investigates police conduct says no charges are warranted against a Halifax police booking officer after an inmate was found unconscious in a jail cell last year.

But the Halifax police are investigating after the Serious Incident Response Team asked it to consider whether the special constable breached policy on when and how he conducted cell checks.

The agency released its report Friday on the June 13 incident, during which a man was taken to a holding cell after a convenience store robbery.

The report says the man laid on his back and remained completely motionless for seven hours after taking drugs. It says the officer's checks were, at best, "brief glances."

The failure to wake or move the inmate may have contributed to his deteriorating medical condition, it says.

Checks are required every 15 minutes, the report says, and the physical and mental condition of inmates must be logged.

The man was taken from the holding cell to hospital, where he remained in a coma for five days.

He later pleaded guilty to robbery and wearing a mask and was sentenced to four years in jail.