What can happen when the police face the possibility of domestic violence in their own ranks? On the night she broke up with her Florida deputy sheriff boyfriend, Michelle O'Connell was found dead from a gunshot in the mouth. Next to her was her boyfriend's semi-automatic service pistol. The sheriff's office called it suicide, but was it? FRONTLINE and The New York Times investigate this death of a young, single mother, and what can happen when the police face the possibility of domestic violence within their own ranks.