What is the author's style in She Said Yes: The Unlikely Martyrdom of Cassie Bernall by Misty Bernall?

This book is written by Misty Bernall. She is Cassie's mother and was there, waiting for her daughter to come home the day she was killed. She was part of the story, but also knew the story of Cassie's past. Misty had a unique understanding of how her daughter might have related to her own killers. She had access to Cassie's private notes and records as well as to those closets to Cassie in life. She began writing the book within weeks of her daughter's death.