Woman returns to her father’s house after he dies

In this novel I’m desperately searching for, a young woman returns to her father’s cliffside home after he dies; they hadn’t gotten along, and he had been a magician of sorts, and his house had several ‘magic tricks’ he had set up. His death was suspicious and his daughter tried to find out who killed him and why; in doing so, she becomes the target of the killer. She teamed up with a young man and of course they fell in love; she also trusted her father’s friend, whom it turned out was the killer. Details I specifically remember include: the house had a trick mirror of some sort; her car brakes don’t work as she’s driving from the house down to the small village below; the cover looked like a typical gothic romance novel; and I think the climax involved the killer chasing her on the roof of the house, and he may have been done in by one of her father’s ‘magic tricks,’ which saved the heroine. I cannot remember the title of the book or the name of the author; I read it around 1982 or so, and I’m sure it had originally been published a few years before that. I suppose it would be classified as a mystery or gothic romance; there were no sex scenes in it but the writing always stuck with me. I found the heroine endearing and the revelation of who the killer was to be surprising and sad, since he seemed like a good man who was sincerely trying to help her find her father’s killer.