Italian police have identified a couple from England as the likely culprits after graffiti was scribbled on a wall at the Colosseum in Rome last week, prompting widespread anger.
A bearded young man in a blue flowery shirt was pictured in a video posted on social media on Saturday scratching his and his girlfriend's name with a key on an internal wall of the ancient Roman stone amphitheater. He left the inscription "Ivan + Hayley 23."
Italy's Carabinieri police said they had been helped to identify the couple by photographic evidence but did not name them.
A police source said the man had been placed under formal investigation but the couple had left the country before the authorities could catch up with them.
The man risks a fine of at least 15,000 euros ($16,415) and a jail sentence of up to five years were he to be convicted in Italy.
"This act was offensive to everyone around the world who appreciates the value of archaeology, monuments and history," said Italian Culture Minister Gennaro Sangiuliano.