Human remains found at a property in Rome owned by the Vatican could hold the clue to a 35-year-old mystery.
The bone fragments were found during construction work at the Vatican's embassy to Italy, near the city's famous Villa Borghese museum.
A Vatican statement said experts were trying to determine the age and sex of the remains, and the date of death.
Italian media have speculated they may be those of a teenage daughter of a Vatican employee who vanished in 1983.
The disappearance of 15-year-old Emanuela Orlandi has been widely linked either to organised crime or to an attempt to force the release from prison of Mehmet Ali Agca, the Turkish man who tried to assassinate Pope John Paul II in 1981.
Orlandi's brother Pietro, has campaigned for decades to find out what happened to her. He has accused the Vatican of remaining silent in the case.
But the remains could be those of Mirella Gregori, who disappeared in Rome 40 days before Orlandi and was also aged 15, media also report.
She answered the intercom at her family's apartment and told her parents it was a schoolfriend. She said she was going out to speak to him, and never returned.
Detectives say it is possible that the cases are connected.
"During restoration works in a space annexed to the Apostolic Nunciature of Italy... fragments of human bone were found," the Vatican said in a statement.
It said that as soon as the remains were found the Vatican's gendarmerie informed the Italian authorities, and the Holy See, and an investigation was launched.
The Vatican has said on several occasions that it has co-operated fully with police investigating the Orlandi case.