SPOKANE, Wash. (AP) — Authorities in Washington state say an inmate who killed his cellmate was seeking vengeance against the convicted child rapist who preyed on his younger sister. The Spokesman-Review reported that 25-year-old Shane Goldsby faces a first-degree murder charge in connection to the June 2 death of his cellmate 70-year-old Robert Munger at Airway Heights Corrections Center. Surveillance video shows Goldsby punching, kicking and stomping on Munger’s head in a common area of the prison. Munger died three days later. A State Department of Corrections spokeswoman said a range of information is used to determine housing assignments but nothing indicted the two knew each other. An investigation is ongoing.