The tusk had been taken off the elephant yesterday in Kebethigollawa while he was lying injured.
The elephant, about 40 years old, had been injured after a confrontation with another elephant and was being treated for his injuries by the Department of Wildlife Conservation office in Anuradhapura.
The animal had been lying on a side because he was being treated for his injuries and had been immobile.
A wildlife official said in a situation like this normally, the range is informed and they keep a watch on the elephant but the attack had happened when no one had been near the animal.
A group of people, and not an individual, are likely to have been involved in the attack.
The DWC has started an investigation into the incident.
