Gregory U. Powell is shown in an undated photograph released to Reuters August 13, 2012. Powell, whose murder of a Los Angeles police officer was chronicled in the 1973 best-selling book "The Onion Field" and a movie of the same name, died August 12, 2012, of natural causes in the California Medical Facility in Vacaville, according to an announcement from The California Department of Corrections and Rehabilitation August 13, 2012. REUTERS/California Department of Corrections and Rehabilitation/Handout

Full Story: "Onion Field" killer dies in California prison at 79