RIO DE JANEIRO (AP) -- Police in the Brazilian city of Sao Paulo are baffled by a macabre puzzle: someone has been leaving gift-wrapped human skulls around town.

Investigator Paul Henry Bozon Verduraz described the case to the Folha de Sao Paulo newspaper in a story published Thursday.

The first skull in cherry-red wrapping was found on February 20 in a planter near a residential building downtown. Since then, seven others have been found near Mormon temples or consulates, including those for Russia, the Czech Republic and South Africa. The skulls are old, with traces of dirt.

Verduraz says security cameras captured images of a woman in an ankle-length skirt leaving the skulls, which seem old, with traces of dirt. He thinks this may be part of some sort of ritual.