(CNN) -- Two U.S. tourists unknowingly bought six human skulls in Greece, which they learned when they were stopped at the airport in Athens.
The Americans carried the skulls in their hand luggage, which was scanned during a layover on their way back to the United States from the island of Mykonos.
The pair were arrested Thursday, accused of desecrating the dead. A coroner later confirmed that the skulls were human, police said.
"The two young tourists said they had bought the skulls in a souvenir shop on the island of Mykonos and believed they were fake," a police spokesperson said.
"They bought them ahead of Halloween to decorate their homes. Both tourists were then released and took a flight back to the U.S."
There was no immediate word on where the skulls originated.