Merline Port-Louis knew she was a woman in danger. In the weeks before she was shot to death early Saturday morning, her estranged boyfriend, Marlon Fann, called and threatened to kill her and her family three times, Nassau police said. Port-Louis took the appropriate measures: She made copies of the threats, filed charges with police and got a panic button to press in case of emergency. But neither her efforts nor those of police were enough to stop Fann from pulling out a gun and shooting Port-Louis in the driveway of her New Cassel home, and then calling her mother...