There are animals whose varied diets allow for an easy way to dispose of carcasses. Many animals are omnivores, which allow them to easily consume meat as well as plants. Carnivores are an obvious choice when discarding parts of corpses, as they are most happy with a pile of meat to eat. A good way to dispose of body parts is to cut it into manageable chunks off the bone and feed it to a carnivore, such as a lion, wolf, or other such creature.
The only issue with that process, are the bones that tend to be left over after the carnivores are done with the flesh and muscle. That can be circumvented by bleaching and pulverizing the bones once the meat is consumed.
The reputation of these fierce Amazon fish is well known. While they are carnivores, it would be rather hard for these fish to devour a full corpse. While this method might be impractical, there might be a way for a well connected individual to use piranhas to dispose of a corpse.
-300 to 500 hungry piranhas
-dismembered body parts
Locate the tank of hungry piranhas. It might be necessary to sneak into an aquarium or bribe the piranha keepers to not feed their charges for the better part of the week.
Abrade the surfaces of the dismembered body parts with the box grater, allowing the pieces to become bloody.
Drop the body parts into the tank. Within an hour, the flesh should be stripped clean of the bones.
Remove the bones from the tank and allow them to dry before bleaching and pulverising.