Dean Koontz Book? about man killing his wife by pushing her off Lookout Tower?

Help! I am trying to remember a book about a man that kills his pregnant wife, by pushing her off a lookout tower. Then tries to kill the detective in charge of the case, and is not succesful. The detective "haunts" the killer. Also I believe in this same story is a young gifted child that is some how tied in and is befriended by the detective. I might be confusing two books, but if you know please help!