The death of Mikayla Miller, a 16-year-old from Hopkinton, is a deeply personal and emotional loss for her family. But since Miller's body was found last month, it's become something else: a case study in the distrust an increasingly wide segment of Americans have for law enforcement — and a political crisis for Middlesex County District Attorney Marian Ryan, who's leading the investigation into Miller's death. Zoe Mathews talks through what’s known, what remains unknown, and how things might develop, with two GBH reporters who've been following the case closely: Tori Bedford and Phillip Martin.