The Vatican has reopened an investigation into the disappearance of Emanuela Orlandi, who went missing as a 15-year-old in 1983.
Ms Orlandi, whose father was an employee of the Holy See, disappeared on June 22, 1983 after leaving her family's Vatican City apartment to go to a music lesson in Rome.
For nearly 40 years her family have been searching for answers, with the unsolved mystery gripping Italy.
As the years went on, theories linked her disappearance from everything from the plot to kill John Paul II to financial scandals involving the Vatican bank to Rome's criminal underworld.
Here's what we know about the investigation and what led to this point.
Why is the Vatican investigating now?
A statement published by the Vatican on Monday, local time, said the decision to reopen the investigation was "partly in response to several requests made by Ms Orlandi's family".
Pietro Orlandi, Ms Orlandi's brother, has been campaigning to compel the Vatican to reveal everything it knows about his sister's disappearance for decades.
He believes the Holy See is hiding information in the case because it might implicate high-ranking figures in the church.
In December, the Orlandi family and opposition senator Carlo Calenda pushed for a parliamentary commission of inquest into the disappearance of Emanuela Orlandi, along with two other cold cases.
Senator Calenda said the Vatican's longstanding official claim of ignorance about Ms Orlandi's disappearance was "hardly credible".
"We are a great secular nation that treats the Vatican with respect, but this case certainly cannot be considered closed in this way," he said.
Three previous initiatives in the Italian Parliament to get answers about Ms Orlandi's disappearance had failed to achieve much.
But last month, the Orlandi's lawyer, Laura Sgro, said she was hopeful this attempt would be successful, given the recent seating of a new legislature and the Catholic Church no longer holding the same political sway as it did in previous decades.
What else may have contributed to the timing of this?
Archbishop Georg Gänswein, who was the longtime personal secretary of the late Pope Emeritus Benedict XVI, is about to publish a tell-all book about the goings on at the Vatican.
His publisher says the book will address the disappearance of Ms Orlandi.
A press release about Archbishop Gänswein's book was published after the former pope's death on New Year's Eve.
"Today, after the death of the pope emeritus, the time has come for the current prefect of the papal household to tell his own truth about the blatant calumnies and dark manoeuvres that have tried in vain to cast shadows on the German pontiff's magisterium and actions," it said.
This comes after the October release of the four-part Netflix documentary series called Vatican Girl, which covers several theories about her disappearance.
The series also provided new testimony from an anonymous woman identified in the documentary as a friend of Ms Orlandi.
The woman said that, a week before Ms Orlandi went missing, the 15-year-old told her someone close to then Pope John Paul II had bothered her while she was walking in the Vatican gardens, inferring the teenager was referring to sexual advances.
Didn't the Vatican already open a tomb linked to this case?
Yes.
In 2019, the Orlandi family received an anonymous letter earlier saying the 15-year-old's body might be hidden in the Vatican's Teutonic Cemetery.
The letter told them to search near a statue of an angel holding a book that reads 'Requiescat in Pace', is Latin for "Rest in Peace".
Months later, the Vatican opened two tombs in the area, which was where the bones of two 19th century princesses were supposed to be.
The Vatican said the exhumation was done in the "spirit of collaboration and attention to the requests made by Emanuela Orlandi's family".
But nothing — not even the bones of the princesses — was found.
"They went down and found a room measuring 4 meters by 3 meters, which was the first surprise … there was absolutely nothing inside," Mr Orlandi said.
A press release from the Vatican later said "several hundred partially intact bone structures, and thousands of fragments", were found in two ossuaries, which are chambers for bones of the dead, under the flooring in a nearby area.
But a morphological analysis of the remains showed they were too old to match the timeline of Ms Orlandi's disappearance.
"The fragments that were found can be dated back to before the disappearance of poor Emanuela," a Vatican statement said.
"The most recent of them dates to at least 100 years ago."
In 2018, human bones were found at the Vatican’s embassy in Rome, sparking much speculation.
But judicial sources later said DNA testing revealed the bones were male and carbon dating showed they predated 1964.
In 2005, an anonymous caller to a television talk show said the secret to Ms Orlandi's disappearance was buried along with Enrico 'Renatino' De Pedis, a mobster who once led the feared Magliana gang that terrorised Rome in the 1980s.
In 2012, police opened his crypt inside a Rome basilica, but nothing came of the exhumation.
ABC with wires
