A man was charged Monday with the weekend killing of an off-duty Birmingham policeman.  40-year old Patrick Johnson of Ensley is charged with capital murder. Investigators say Johnson shot and killed Officer Keary Hollis, after the men argued in the parking lot of a Bush Boulevard convenience store. Johnson ran after Hollis as he drove off, firing four shots into the car, witnesses said. The men argued, after Hollis accidentally hit Johnson's parked motorcycle with his car, knocking it over.