Daddys Little Girl by Mary Higgins Clark

Ellie Cavanaugh was only seven when her older sister, Andrea, was murdered near their home in rural Westchester County. It was Ellie's testimony that led to the conviction of a man, who steadfastly denied his guilt, but spent twenty-two years in prison. When he comes up for parole, Ellie protests, but the convicted killer is set free and returns home. Ellie also returns, intent on writing a book that will prove his guilt. But as she delves deeper into her research, she uncovers horrifying facts that shed a new light on her sister's murder. And with each discovery, she comes closer to a confrontation with a desperate killer...