When her daughter Karen was kidnapped in 2014, Miriam Rodr\xedguez knew the Zetas, a cartel that ran organized crime in her town of San Fernando, Mexico, were responsible.\nFrom the hopelessness that her daughter may never return came resolve: She vowed to find all those responsible and bring them to justice.\nOne by one, Ms. Rodr\xedguez tracked these people down through inventive, homespun detective methods.\nToday, we share the story of her three-year campaign for justice.