A man who was convicted of killing two Prescott Valley residents in 2012, and was serving a death sentence for the crimes, has been killed in prison. The state Department of Corrections says 38-year-old Kenneth Wayne Thompson was in a housing unit at the state prison in Florence, when two inmates attacked him last Wednesday. Guards found Thompson with life-threatening injuries in his cell. He was pronounced dead later that day. Thompson was convicted of February of 2019 of killing his sister-in-law, 35-year-old Penelope Edwards and her fiancé, 38-year-old Troy Dunn, both of Prescott Valley in 2012. Thompson killed the two, then set their house on fire. He was pulled over in Flagstaff for a traffic violation and was arrested after evidence of the murders was found in his car. The jury sentenced him to death in the case. The two inmates responsible for the attack on Thompson have been found and an investigation is underway.