(CNN) - The infamous "Onion Field" cop killer whose 1963 crime was chronicled in a best-selling book and a movie has died, officials said Monday. He was 79.
Gregory Powell died Sunday at the California Medical Facility, a prison in Vacaville, the California Department of Corrections and Rehabilitation said in a statement.
In October, Powell was denied compassionate release, all but guaranteeing he would die behind bars.
He had cancer, according to the Los Angeles Police Protective League. Prison officials, however, never confirmed that account and Monday's statement said simply that Powell died of "natural causes."
He was serving a life sentence with the possibility of parole for killing Los Angeles Police Officer Ian Campbell nearly 50 years ago.