Necropsy Provides New Clue Into Mysterious Deaths of 13 Bald Eagles on Maryland Farm

— -- Newly released necropsy results are providing a new clue into the mysterious deaths of 13 eagles found on a farm last month in Federalsburg, Maryland, according to the U.S. Fish and Wildlife Service.

"The results show that these eagles did not die of natural causes, including disease," U.S. Fish and Wildlife public affairs specialist Catherine J. Hibbard told ABC News today in a statement.

The necropsy ruled out diseases such as avian influenza as a cause of the mass death, Hibbard said.

"Our investigation is now focused on human causes and bringing to justice the person(s) responsible for the death of these eagles," she said. "We cannot release further details about the cause of death as such information may compromise the ongoing investigation."

The U.S. Fish and Wildlife Service is working with the Maryland Natural Resources Police to solve the case, Hibbard said. She added that there is a $25,000 reward for information leading to the arrest and conviction of suspected wildlife offenders.

Killing a bald eagle is a federal offense punishable by up to $250,000 in fines and possibly up to two years in prison.