Popular high school teacher allegedly guns down hubby’s new girlfriend decorating Christmas tree in front of tot twins

Chelsea Cook, a health teacher at a Salt Lake City high school, allegedly fatally shot her ex-husband's girlfriend while visiting her children to deliver cough medicine. The girlfriend was reportedly helping the kids decorate their father's Christmas tree when the attack happened in the apartment. Nancy Grace looks at the shocking case with former detective Steven Lampley, North Carolina family & divorce lawyer Kathleen Murphy, New York psychologist Caryn Stark, and Crime Stories reporter Nicole Partin.