The state Medical Examiner’s Office said Friday that inmate Stephen Ray Gravel’s death at the Maine State Prison in Warren this week was due to lung cancer.

Mark Belserene, a spokesman for the chief medical examiner, said in an email that further details about the death of the 53-year-old former Oxford resident will not be available until a final report is completed.

Gravel died early Tuesday morning, prison officials said. He was serving a five-year sentence after pleading guilty to gross sexual assault in Oxford County Superior Court in South Paris in 2012.