An incarcerated person serving a life sentence was found dead by correctional officials in a Northern California prison.

Stephenson C. Kim, 45, was convicted for six counts of murder and one count of street terrorism and received life without parole for a 2004 shooting. 

On January 4, Joe Duty Jr., 30, and Kim were identified as participants in a violent altercation that resulted in Kim’s death, according to CBS News.

According to prison officials, at approximately 7:20 p.m., staff responded to an incident between Kim and Duty at the California Medical Facility in Vacaville, California.  As a result, Kim was discovered unconscious. Staff performed CPR and Kim was taken to the facility’s emergency room.

Kim was then transferred to an outside medical facility where he later passed away. At the time of the altercation, both men received medical attention. 

Duty, who survived the altercation, has been medically evaluated and placed in the Restrictive Housing Unit pending an investigation. 

The prison’s Investigative Service Unit and the Solano County District Attorney’s Office will conduct the investigation, noted CBS.

“I wonder what the reason for the altercation [was]. [It] most likely could have been prevented,” said San Quentin resident Emilio Lamas.