The Hawaii Department of Public Safety announced Friday that a 21-year-old inmate from Hawaii was found unconscious in his cell at an Arizona prison Thursday afternoon, and later pronounced dead at the hospital. 

His cellmate Jason McCormick, a Hawaii inmate serving time for second-degree murder, hit the distress button at 3:15 p.m. Thursday and advised officers his cellmate needed medical attention, Public Safety officials said in a news release. 

Sagauro Correctional Center corrections officers found Jonathan Namauleg unconscious and lying face down on his cell floor. 

An emergency response team and medical staff arrived in minutes and began cardiopulmonary resuscitation on Namauleg. He was taken by ambulance to a hospital, where he was pronounced dead at about 5 p.m. Thursday. 

An autopsy is pending. 

Eloy, Ariz., police are investigating the incident and are treating the cell as a crime scene. 

The Hawaii Department of Public Safety investigators are also going to Arizona to investigate. 

Namauleg was serving a three-year sentence for third-degree arson.

McCormick was sentenced in September 2013 for the strangulation of Robert T. Henderson, a visiting University of Pittsburgh professor, whose body was found in a Waikiki apartment in July 1996.

The murder had been a Honolulu police cold case until McCormick confessed in 2008, saying that he killed Henderson after the professor allegedly made unwanted advances.