The discovery of human bones in a Vatican building in Rome has prompted investigators to reopen a murder case shrouded in mystery and speculation for 35 years.

The Rome prosecutor’s office has ordered DNA tests amid speculation the remains could belong to Emanuela Orlandi or another teenage girl who disappeared a month before her, Mirella Gregori.

The bones were found during renovation works at the Vatican embassy in Rome, a Vatican statement said.

Emanuela Orlandi’s image was a constant presence on Rome’s streets when she first went missing. Photo: L’Osservatore

Orlandi was a Vatican citizen, the 15-year-old daughter of a Vatican clerk, who went missing in 1983 after attending a flute lesson near Rome’s central Piazza Navona.

On Wednesday, RAI state radio quoted a lawyer for the Orlandi family as saying that she would file a motion to “be informed” about investigations.

“Any action, any situation, and discovery puts us in a justified state of alert,” Annamaria Bernardini de Pace said. “We would do anything just to know what happened,” she added.

Over the years, a series of conspiracy theories has connected her disappearance to anti-papal plots by foreign secret agents, Italian mobsters and sexual predators within the clergy.

Last year, Italian investigative journalist Emiliano Fittipaldi published what he claimed was a Vatican memo suggesting that Orlandi was kept hidden in London for years, but this was also unproven.

“We are asking Rome prosecutors and the Holy See by what means the bones were found and how their discovery was placed in relation to the disappearances of Emanuela Orlandi and Mirella Gregori,” lawyer Laura Scro said, adding that the Vatican statement ‘”provides little information”.

Experts say that could be determined within the next 10 days if adequate DNA can be extracted from the fragments.