Albany County Undersheriff Rob DeBree says the plane was found in pieces Thursday on the south face of Laramie Peak, and there were no survivors.
Earlier he said four people were on the plane for business. Their names weren't immediately released.
DeBree says crews plan to recover the wreckage early Friday.
The search for the Piper PA-32 had been led by the Wyoming Civil Air Patrol, a U.S. Air Force helicopter and ground crews.
The plane had been scheduled to land Tuesday evening at the Casper airport after taking off from Marshall, Texas, and stopping for fuel in Dodge City, Kan.
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