The mutilated carcasses were torn to shreds and scattered across moorland near to the Devil's Bridge in the Cambrian Mountains near Aberystwyth, west Wales.
The area has long been linked to the so-called “Beast of Bont”, a big cat believed by some to have been on the loose for decades.
Locals have reported sighting of an unknown creature since the 1970s, and now fear the predator could have struck again.
Mark Davey, 43, discovered the latest "sickening" scene and insists the attacker could not have been a fox or a dog.
He said: "The whole area just stank of dead animals and was quite sickening. I could see that the inside of the animals had been ripped out and body parts were lying all around.