In 1997, archaeologists working in Leonding in Austria found a deep pit which dated to c. 200BC. It contained remains of humans and animals, all apparently subjected to burning. Its been interpreted as the focus of a sacrificial ritual where humans and beasts were tethered to a wooden device suspended over the pit which was then set on fire. Then the whole thing, including victims, collapsed into the pit.

While this does not prove the existence of a wicker man, it does seem to substantiate that fire was an important method by which humans could transcend to the gods.