Federal wildlife officials are investigating the killing of a wolf near Custer, in western South Dakota's Black Hills.
U.S. Fish and Wildlife Service special agent Brad Merrill says samples have been sent to a laboratory in Washington state to determine if the animal is "pure wolf."
The gray wolf is on the state list of rare, threatened or endangered species, and sightings are rare. John Kanta with the state Game, Fish and Parks Department says the last confirmed wolf in western South Dakota was hit by a vehicle in March 2006.
Officials have not released details of the recent wolf killing.