Shadow of a Broken Man — George C. Chesbro

Meet Dr. Robert Frederickson, a.k.a. Mongo. He has a Ph.D. in criminology and a black belt in karate. He teaches at a university, and is a private detective who specializes in solving cases that Sam Spade would have found too kinky to cope with. And, just incidentally, he happens to be a dwarf.

In short, Mongo is a man to look up to as he plunges into the pits of human perversity to find a corpse who wouldn't die and a killer who wouldn't stop....