A serial bank robber suspected of murdering a Mississippi police officer and wounding a second one was killed in a shootout with cops in Arizona on Saturday, ending a weeklong manhunt, according to NBC News. Mario Edward Garnett, 40, ran out of a bank with a mask on and a gun in his hand and was shot by a plain clothes officer after he started shooting at agents who were called to the scene, said Phoenix Police Department spokesman James Holmes. Officials believe Garnett is responsible for similar bank heists in Atlanta and Tupelo, Miss., where he allegedly shot two officers, killing one. Minutes after the robber struck a BanCorpSouth in Tupelo on Monday afternoon, Tupelo Police Department sergeant Gale Stauffer and his partner, Officer Joseph Maher, raced to the scene and stopped a car on the road. The suspect was in the vehicle behind, jumped out and ambushed the officers, police said. Stauffer was killed and Maher was seriously hurt.