Secrets To The Grave by Tami Hoag

Marissa Fordham had a past full of secrets, a present full of lies. Everyone knew of her, but no one knew her. When Marissa is found brutally murdered, with her young daughter, Haley, resting her head on her mother's bloody breast, she sends the idyllic California town of Oak Knoll into a tailspin. Already on edge with the upcoming trial of the See-No-Evil killer, residents are shocked by reports of the crime scene, which might not have been discovered for days had it not been for a chilling 911 call: a small child's voice saying, "My daddy hurt my mommy." Sheriff's detective Tony Mendez faces a puzzle with nothing but pieces that won't fit. To assist with his witness, Haley, he calls teacher-turned-child advocate Anne Leone. Anne's life is hectic enough⁠—she's a newlywed and a part-time student in child psychology, plus she's the star witness in the See-No-Evil trial. But one look at Haley, alone and terrified, and Anne's heart is stolen.