The raid happened late on Saturday night and involved between three and five robbers.
There was speculation that they had kept the Bulgari store under surveillance for some time and may well have gone into the shop, posing as customers, to better understand its layout and security systems.
The gang reportedly left behind a crowbar but given the sophistication of the operation, it is likely they all wore gloves and did not leave any fingerprints.
‘Hollywood on the Tiber’
In August 2022, a similar tunnelling technique was used by a gang of thieves to try to raid a bank near the Vatican.
On that occasion, the thieves dug a tunnel from an abandoned shop, hoping to access a bank branch.
But one of them, dubbed “the mole man” by the Italian press, became stuck for more than eight hours when a section of the tunnel collapsed.
He was eventually extricated alive with the help of a large mechanical digger.
The other members of the gang tried to flee the area but were caught by police.