Honolulu police have opened a first-degree murder investigation today in the death of a 31-year-old male inmate at Halawa Correctional Facility.

Police said in an update today that the Medical Examiner’s Office ruled Thursday that the inmate’s death was a homicide.

The Medical Examiner’s Office has not released to the public the person’s identification, nor the cause of death.

The inmate was found unresponsive in his cell Tuesday at 2:23 p.m. after reportedly being assaulted, police said.

He was taken to the hospital, where he was pronounced dead 5:24 p.m. Wednesday.

The investigation is under the jurisdiction of the Department of the Attorney General. Honolulu Police Department’s Criminal Investigation Division and its Scientific Investigative Section assisted with the initial investigation, police said.