AdvertisementOpen Cases: Why One-Third Of Murders In America Go UnresolvedMarch 30, 2015Martin KastefacebookEmailDetective Mark Williams (right) speaks with an officer in Richmond, Va. A decade ago, amid a surge in violent crime, Richmond police were identifying relatively few murder suspects. So the police department refocused its efforts to bring up its "clearance rate." (Alex Matzke for NPR)