That idea spawned Skeleton Lake, a documentary that offers the best explanation yet on the mystery of Roopkund, to be aired on the National Geographic Channel on November 9. It's part of a series called Forensic Investigation Report, which examines mysteries from all over the world—these range from the strange alchemy behind the liquefying blood of San Gennaro, one of Italy's most famous religious events, to uncovering the story of a 700-year-old murder in Peru.
Though there were several theories on how the bones got there, none seemed to stand up to rigorous analysis. National Geographic and Miditech figured that one way to get a better set of answers to the Roopkund riddle would be to attack from several sides, through many disciplines.
One of the first people they spoke to was professor William Sax, a cultural anthropologist at Germany's Heidelberg University. Sax enjoys the sort of acclaim in his field that, say, a Tendulkar might in cricket. He has been studying the hill people and their collective memories and myths for decades. He was familiar with a traditional song sung by women of the area which describes the rage of the goddess Nanda Devi at interlopers who sacrilegiously brought carnal behaviour into her sanctuary. She rained death upon them, with hailstones "hard as iron". Sax wondered how this belief might connect with the team's findings.