A Shasta County killer has died in prison, possibly at the hands of his cellmate. 36-year-old Joshua McCormick was found unresponsive in his cell Tuesday morning, according to staff at the Mule Creek State Prison. McCormick arrived at the prison in Ione 2 years ago to begin a sentence of 150 years to life for 3 counts of first degree murder and one attempted murder. McCormick and Rebecca Wilson murdered Michael Forsyth and Tommy Burton during a burglary in 2013 at the Ingot Auto Dismantlers on Highway 299 northeast of Redding. One was shot while running away and the other was shot execution-style inside a trailer. A safe was taken that contained old coins, stamps, watches, jewelry, and other items. A third burglar who was with McCormick and Wilson was 31-year-old Eric Ratledge. About a week later Ratledge was shot in the head by McCormick. That killing happened at a house on Rancho Road that has since burned down. Ratledge’s body was found in the bed of a burning pickup truck on Millville Plains. McCormick, seeking to avoid a death sentence, made a plea deal for his life sentence. The suspect in McCormick’s killing has been imprisoned since 2001, serving a life sentence for murder.