Is it possible you're thinking of the Mongo series? It features a dwarf detective, a former circus acrobat, who solves crimes, sometimes with horror and mystical elements.
Meet Dr. Robert Frederickson, or "Mongo" to his friends. He's a former circus tumbler, black belt in karate, doctor of Criminology, and professor at a New York City university. And he's quite an unusual fellow as well, not only because he's a private investigator but also because he's a dwarf...
The Fear in Yesterday's Rings looks like the most likely match for the particular plot:
A rash of hideous killings throughout the Great Plains seizes the imagination of the more lurid tabloid newspapers, which bray WEREWOLF! Hunters and gun buffs have been torn to shreds and partially devoured.
Mongo finds himself in the heartland on a mission of mercy for old friend Phil Statler, former owner of the Statler Brothers Circus. Many years ago, Phil spirited young Robert Frederickson away from a painful childhood in Nebraska and secured him fame as the star acrobat "Mongo the Magnificent." Mongo, now in league with Harper Rhys-Whitney, a snake charmer of seductive beauty and diminutive stature, backed financially by an entire Florida town of wealthy ex-circus freaks, hopes to buy back the circus from the mysterious new owners and restore Statler as its head.
But the trail of the circus and the trail of the "werewolf" cross. Behind the scenes at the big top, Mongo encounters a pair of outlandish international criminals---a brilliant genetics scientist and a wild animal trainer of uncanny talents. Surely it's not a coincidence that corpses, not just handbills and popcorn boxes, are left in the wake of this traveling show.
Once the star, Mongo finds himself back in the center ring...in the Deadliest Show on Earth.