Around 8:50 a.m. on Feb. 24, an officer at the North Kern State Prison in Delano was conducting a security and welfare check when they spotted Juan Villanueva, 53, unresponsive in his cell, according to the California Department of Corrections and Rehabilitation.
Prison officials immediately called for help and staff members conducted lifesaving measures on Villanueva.
He was taken to the prison’s triage area via ambulance and was pronounced dead at 9:03 a.m., officials said.
An autopsy was being conducted by the Kern County coroner and the investigation into Villanueva's death is ongoing.
Escobar was sentenced to life in prison without parole in May for two counts of first-degree murder. He also received a life sentence for three counts of first-degree murder and seven counts of attempted murder.
He was arrested in 2018 after he beat and killed several people in downtown Los Angeles and Santa Monica while he was homeless, according to the Los Angeles Times.
Never miss a story — sign up for the Front Page Detectives newsletter. Be on the scene the moment news breaks.
All of Escobar's victims were also homeless, except for one, and several were beaten so badly they were left comatose. The serial killer reportedly used a baseball bat and bolt cutters during his attacks.
The Los Angeles Times reported Escobar fled Houston after he killed his aunt and uncle, Dina and Rogelio Escobar, and ended up on the West Coast.
Become a Front Page Detective
Sign up to receive breaking
Front Page Detectives
news and exclusive investigations.