A Massachusetts jury is set to confront one of the most harrowing criminal cases in recent memory as the murder trial of Lindsay Clancy begins Monday, more than three years after prosecutors say she strangled her three young children inside the family's home.
At the heart of the trial is a question that has divided legal and medical experts: Was Clancy a calculating killer, or was she gripped by a rare psychiatric illness that left her unable to understand what she was doing?