Updated

Police are scratching their heads trying to work out who donated a human skull to a thrift store in Austin, Texas.

Homicide Detective Derek Israel said Wednesday that foul play is not suspected and that he just wants to know how the adult skull came to be left at the Goodwill store.

Goodwill store staff discovered the skull while sifting through donations on July 16. A spokeswoman says it could have been gifted up to a week prior to its discovery.

No other details about it have been released.

This is at least the fourth skull to be donated to the international nonprofit this summer. Three were donated in July to a Goodwill store in Bellevue, Washington.