It has been over seven years since 43 students from the  Ayotzinapa Rural Teachers’ College in Guerrero, Mexico, were taken by armed men in the middle of the night. They were never seen again. Their disappearance sparked mass protests, as the 43 became symbols of Mexico’s unchecked human rights abuses. In recent decades, tens of thousands of people have gone missing in Mexico, and almost no one has been held accountable. The culture of impunity is so ingrained that families often don’t go to police for help, believing they’re either corrupt or too afraid to investigate. In a three-part investigation of the Ayotzinapa case, Reveal’s Anayansi Diaz-Cortes and Kate Doyle from the National Security Archive take us inside the investigation into the attack on the students. They have help from Omar Gómez Trejo – the man the Mexican president tapped to prosecute the crime. For more than a year, he kept audio diaries and had regular conversations with Diaz-Cortes and Doyle, giving them insight into a massive coverup by the previous Mexican administration and efforts by current investigators to piece together the details of the attack and bring to justice those responsible.