The reward for information in the case, jumps to $16,000.
Last November, someone found an injured whooping crane near pond river. Wildlife officials had to put the bird down.
Since the crane and its mate were carrying radio transmitters,authorities were able to track down the body of the second bird not far away.
Whooping cranes are an endangered species protected by federal law.
Less than 500 of them live in the wild, seven of them have been wintering in Western Kentucky this year.
Killing a whooping crane can carry up to a year in prison and a $100,000 fine.