DECATUR, Georgia — A Georgia Bureau of Investigation crime lab expert tells CNN how-using bullets from the victim and shell casings from the crime scene-she was able to identify the type of gun the killer used in December to ambush DeKalb County sheriff-elect Derwin Brown. In a red brick office building outside Atlanta, a tall woman in a Georgia Tech sweatshirt saunters down the hall. In one hand, she's carrying a 9 mm Tec 9 machine pistol, in the other, a clip full... (GunPolicy.org)