ROME — Thirty-six years ago, the teenage daughter of a Vatican City employee vanished off a Rome street on her way home, beginning one of Italy’s most enduring mysteries: Over the years, reports have variously linked her fate to the Sicilian Mafia, the K.G.B. and the plot to assassinate Pope John Paul II.

On Thursday, the latest trail led her family and a Vatican-appointed forensic scientist to two tombs inside the Vatican walls, the burial places of princesses well over a century dead.

The team only found another mystery: The tombs were empty. Even the bodies of the dead princesses were missing.

It was yet another strange turn for a family that has suffered false leads, red herrings and intense media attention since the girl, Emanuela Orlandi, disappeared at age 15 on June 22, 1983. Their quest to discover her fate has taken them down many tortuous paths, following up on tips, anonymous letters and reports of sightings.