Mindy Called the Police Reporting a Robbery at the Bar

Mindy called the police reporting a robbery at the bar next to her place of business. Two police officers arrived at the scene. As one police officer surveyed the scene, the other officer called for back-up. When the officer approached the back of the bar, the suspect ran out of the front door. The police called for the suspect to stop, but he kept running. As the suspect approached a chain link fence, the officer told him to stop one last time. The suspect began to climb the fence, and the officer shot the suspect in the head. The suspect died on the spot. When is a police officer justified in using deadly force? In this case, was the officer justified? Why or why not? What if the suspect had been running with a hammer in his hand? Would the ruling be different? Why or why not?