The carcass, found at a place close to Argalbindha village in Tunguru forest area of the sanctuary yesterday, was of a female elephant aged more than 60 years, senior forest officials said.
It seems the animal died a natural death and no injury mark was found on its body, they said.
A team of veterinary doctors from Bisoi visited the spot for autopsy and details would be known after the postmortem, they said.