A prison inmate is dead and the circumstances surrounding his death are under investigation.

Stephen Ray Gravel, age 53, had served approximately 5 years of a 16 year sentence for gross sexual assault, according to a press release received this morning from the Maine Department of Corrections.

Gravel’s death at the Maine State Prison in Warren was discovered around 5:45 this morning.

Both the Medical Examiner’s Office and State Police are investigating.