A genetics expert retained by the family of an Italian girl who went missing in 1983 said Saturday that an underground space near a Vatican cemetery holds thousands of bones that appear to be from dozens of individuals, both “adult and non-adult”.

Giorgio Portera, said the “enormous” size of the collection under the Teutonic College was revealed when Vatican-appointed experts began cataloguing the remains, which were discovered last week.

“We didn’t expect such an enormous number” of bones and other remains which “had been thrown into a cavity,” Mr Portera said. “We want to know why and how” the bones ended up there.

Fragments were also found, complicating the forensic experts’ work, he said.

Vatican Missing Girl
Bones were found under a slab in the Teutonic Cemetery (Gregorio Borgia/AP)

Mr Portera is working on behalf of the family of Emanuela Orlandi, who vanished at the age of 15 after she left her family’s Vatican City apartment for a music lesson in Rome. What became of her is one of Italy’s most enduring mysteries.

Some have theorised that she was kidnapped in an unsuccessful ransom bid to win freedom for the Turkish gunman who shot and wounded Pope John Paul II in St  Peter’s Square in 1981.

A Vatican statement Saturday made no mention of the number of remains in the newly discovered space near the Teutonic Cemetery, but said the forensic work would resume on July 27.

Miss Orlandi’s family previously received an anonymous tip to search near the 19th century tombs of two German princesses in the tiny graveyard.

But when the Vatican opened the tombs recently at the family’s request, they were empty.

The Vatican said it did not know why, but indicated restoration work in the cemetery area in the 1960s and 1970s might be a reason.