A 41-year-old inmate has died in prison near Grafton, in the Northern Rivers region of New South Wales.
The man was found unresponsive in his cell at Clarence Correctional Centre by staff at 12:05pm on Saturday and was pronounced dead half an hour later.
Serco, the operator of the facility, has issued a statement saying Serco, Corrective Services NSW, and NSW Police are investigating the incident.
All deaths in custody are subject to a coronial inquest, and police have confirmed a report will be prepared for the NSW Coroner.