Rome (CNN)The Vatican has ordered two of its own tombs to be searched -- the latest twist in the mysterious disappearance of a teenager, 36 years ago.
Emanuela Orlandi was 15 when she vanished without a trace in the summer of 1983. The daughter of a prominent employee of the Institute for the Works of Religion -- better known as the Vatican Bank -- Orlandi was last seen at a music lesson in the grounds of Sant'Apollinare basilica in Rome.
On Tuesday, Gian Piero Milano, the Vatican's Promoter of Justice, authorized two exhumations in response to a petition launched by the teenager's family, who believe that her body is buried at the Teutonic Cemetery in Vatican City.
Orlandi's mother and brother still live inside the Vatican's walls and have continued to push for her case to be investigated throughout the years. The family's lawyer received an anonymous tip last summer suggesting that they should "seek where the angel indicates," Italian news agency ANSA reported.
The clue led the family to a wall in the Teutonic cemetery which features an angel pointing. The tombs will be opened on Thursday July 11, Vatican spokesman Alessandro Gisotti announced Tuesday.
Gisotti described the case as "a long and painful one" but also appeared to try to temper expectations of a quick resolution, adding that any bones found during the search would have to undergo laborious DNA analysis.
Gisotti said the operation would be a "complex organization of personnel and machinery" involving the Vatican Gendarmerie in addition to Vatican construction workers. He also said the Vatican probe would only handle the part concerning territory in the Holy See. Over the years, the wider investigation into Orlandi's disappearance has been handled by Italian authorities since she vanished in Italian territory.
The Teutonic Cemetery is adjacent to Saint Peter's Basilica. It contains the remains of the Swiss Guards who died defending the Vatican City against forces of the new Kingdom of Italy in 1870. It is also the reserved burial ground for members of German-speaking religious institutions in Rome.
The Orlandi case has enthralled Italians and sparked numerous conspiracy theories, which have pointed the finger at everyone from the Mafia to the Vatican itself.
In 2012, a top Vatican exorcist, the Rev. Gabriele Amorth, told CNN he suspected the young girl had been abducted for sexual reasons, adding: "The investigation should be carried out inside the Vatican and not outside."
In 2005, an Italian detective received an anonymous tip off that Orlandi had been kidnapped by order of then-vicar of Rome, Cardinal Ugo Poletti, and that "the secret to the mystery lies in a tomb in Sant'Apollinare basilica" -- specifically the crypt that holds mob boss Enrico "Renatino" De Pedis.
De Pedis was gunned down in Rome in 1990 and his body was moved to the basilica sometime before 1997.