The opening of two tombs inside the Vatican in the search for the possible remains of a girl missing for three decades on Thursday led to yet another mystery: the tombs were completely empty.

The inspection, which took about two hours early on Thursday, sprung from the tireless efforts of the family of Emanuela Orlandi, a 15 years-old Vatican citizen who disappeared in the summer of 1983, to shed light over the fate of the girl.

The Vatican gave the green light to the exhumations after the Orlandi family received an anonymous note last summer, hinting that the girl's remains might be in one of the two graves located in the Vatican's Teutonic Cemetery.

According to the letter, Ms Orlandi’s body would have been found in the tomb which is pointed to by an angel on the cemetery wall holding a sheet saying: “Rest in peace.”

The two adjacent tombs unsealed were the “Tomb of the Angel,” of Princess Sophie von Hohenlohe, who died in 1836, and the tomb of Princess Carlotta Federica of Mecklemburg, who died in 1840.