The Vatican was set Saturday to open ossuaries discovered under a trapdoor as it attempts to get to the bottom of a riddle involving two princesses and a missing teenager.
The ossuaries were found last week under the floor of the Pontifical Teutonic College after the shock discovery that the bones of the princesses had disappeared from two tombs in the Teutonic Cemetery.
The graves of Princess Sophie von Hohenlohe and Princess Charlotte Federica of Mecklenburg had been exhumed after an anonymous tip-off that they may hold the remains of an Italian youngster who went missing 36 years ago.
Emanuela Orlandi, the daughter of a Vatican employee, was last seen leaving a music class in Rome in 1983 aged 15, and theories have circulated for decades about who took her and where her body might lie.
The family had received a picture of an angel-topped grave in the cemetery, and a message which simply read: "Look where the angel is pointing".
But in a surprise twist, not only was there no trace of Orlandi, the remains of the princesses were gone too.
The Vatican said the bones were likely moved during work on the cemetery and college during the 1960s and 1970s.
The ossuaries will be opened by forensic scientists in the presence of an expert appointed by the Orlandi family.
It was not known whether relatives of the princesses, who died in 1836 and 1840, would attend.
Actress and designer Ira von Fuerstenberg, a distant relation to von Hohenlohe by marriage, told Italian media the disappearance of their skeletons was "an incredible... crazy situation".
- 'Seek the truth' -
Forensic anthropologists expect to be able to roughly date the bones within about five hours.
A sample from each set of remains will be taken so that a DNA analysis can be carried out.
Results could take up to 60 days.
Pietro Orlandi, 60, whose mother still lives within the Vatican walls, told AFP he hoped she was still alive.
"I will have to carry on. Until I find Emanuela, it is my duty to seek out the truth," he said.
According to some theories widely circulated in Italian media, the teen was snatched by a mobster gang to put pressure on the Vatican to recover a loan.
Another claim often repeated in the press was that she was taken to force the release from prison of Mehmet Ali Agca, the Turk who attempted to assassinate Pope John Paul II in 1981.
In 2017, conspiracy specialists were driven into a frenzy by a leaked -- but apparently falsified -- document, purportedly written by a cardinal and pointing to a Vatican cover-up.
Five years earlier, experts exhuming the tomb of a notorious crime boss at a Vatican-owned church uncovered some 400 boxes of bones.
Enrico De Pedis, head of the Magliana gang, was suspected of involvement in her kidnapping and some speculated the youngster may be buried alongside him -- but DNA tests failed to find a match.