Mackenzie went to Whitfield, a private prep school in St. Louis, where the school’s wellness director, Ginny Fendell, called her the “queen of compartmentalization.” She got A’s, served in student government, played varsity soccer, managed the field-hockey team, and volunteered for the Special Olympics. She was five feet ten with long curly blond hair—“the picture of Americana,” as one friend described her. Mackenzie’s parents had separated when she was six, and Mackenzie lived with her mother, Carrie Morrison, the director of breast imaging and mammography at St. Luke’s Hospital, in Chesterfield, a wealthy suburb of St. Louis. They liked to imagine themselves as the Gilmore Girls: the single mother and her precocious daughter, so close they were nearly fused. But Mackenzie’s friends and teachers noticed that in her mother’s presence Mackenzie physically recoiled. Lisa Smith, the mother of one of Mackenzie’s best friends at Whitfield, said that her daughter once asked why Mackenzie was always injured: “My daughter kind of looked at me funny, and I looked back at her and said, ‘What are you trying to say?’ ”