Cat to the Dogs (Joe Grey 5) by Shirley Rousseau Murphy
A recent earthquake was only the beginning of the big trouble that plagues Molena Point, California. Joe Grey may be merely a cat, but he's already solved more murders than your average human detective, and he knows the "accident" on Hellhag Hill was anything but. Unfortunately Joe's somewhat erratic, if lovable, owner Clyde thinks cats should keep their paws out of police work, and locks Joe and his feline lady friend Dulcie out of the house when Officer Max Harper pays a social call.
But Joe can be a very stubborn tomcat when he sets his mind to it. And he's not about to give up the hunt. A killer needs to be apprehended, and Joe Grey's just the cat for the job -- especially since the humans who should be on the case don't seem to have a clue.