The eagle was found wounded in Soldiertown Township on the Whitehorse Road.
It's believed the eagle was shot with a shotgun sometime between Wednesday, October 11 and Friday, October 13.
The eagle was badly wounded and needed to be euthanized after veterinary treatment was sought.
The U.S. Fish and Wildlife Service is offering a reward of up to $2,500 for any information leading to the arrest and conviction of the person or persons responsible.
Anyone with information regarding this incident is encouraged to call either "Operation Game Thief," or the U.S. Fish and Wildlife Service Office of law enforcement at (207) 469-6842.