Four human skulls wrapped in plastic and aluminum foil were discovered in a package being mailed to the United States from Mexico on Friday.
The skulls were packaged inside a cardboard box and were located at Queretaro Intercontinental Airport in central Mexico.
Mexico’s National Guard said that they were called to investigate the package after an airport screening x-ray noticed the strange shapes.
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According to the National Guard, the skulls were being sent from the state of Michoacan to an address in Manning, South Carolina.
Michoacan is one of the most violent states in Mexico. The city the skulls originated in, Apatazingan, is currently being dominated by the Viagras drug cartel.
“The National Guard gave no further details on the age, identity or possible motive for the sending of the human remains,” Reuters reports.
There was also no public information about how the skulls were obtained.
According to the Mexican National Guard, the sender may have violated the laws on handling corpses, regardless of where they came from.
A special permit from a health authority is required to transfer or transport human remains, which the sender did not have, according to the National Guard.