WASHINGTON - In Alabama, a man with a history of mental illness killed two police officers with a rifle he bought on Christmas Eve. In suburban New York, a schizophrenic walked into a church during Mass and shot to death a priest and a parishioner. In Texas, a woman taking anti-psychotic medication used a shotgun to kill herself. Not one of their names was in a database that licensed gun dealers must check before making sales — even though federal law prohibits the mentally ill from purchasing guns. Most states have privacy laws barring such information from being shared with...