Psycho 2 by Robert Bloch

You remember Norman Bates-the shy motel manager with the fatal mother fixation. Now, years after his bout of butchery that horrified the world, Norman is at large again, breaking free from the psycho ward, cutting a shocking swath of blood all the way to Hollywood-where, so it happens, they are making a movie about Norman's life and crimes. A movie that suddenly and terrifyingly becomes a lot like real life....