From BBC News:

The first attempt on 11 July exhumed two tombs a tip-off had said might contain Emanuela Orlandi’s remains.

But it only deepened the mystery as even the bones of two princesses thought to be there were missing. Experts on Saturday began examining two ossuaries – small chambers where dead are buried – found in the first search.  Ms Orlandi’s family hopes the search at the Vatican’s Pontifical Teutonic College holds the key to a mystery that has gripped Italy since 1983.