Burglars who broke into a dentist's apartment basement fled without taking a thing after they found eight severed human heads in a trunk, Austrian police reported Friday.

The dentist was storing the mummified heads to use for research. Police said the burglars must have stumbled into them soon after they broke in.

A spokeswoman for the Austrian police tells Reuters, "The burglars were looking for loot when they discovered the heads. From what it looks like, they just left them lying and bolted away."

Austrian authorities say they are investigating whether the dentist breached regulations for the storage of research materials.