A joint investigation involving Swiss and Italian police has uncovered a massive Swiss-Italian antiquities smuggling ring. Police seized 5,361 vases, bronze statues, and frescoes worth an estimated €50 million ($58 million) during a raid on a number of Swiss warehouses, the Guardian reports.

Unveiling the spoils of the investigation, the head of the Italian military police, Carabinieri General Mariano Mossa said, “This is by a long shot the biggest recovery in history in terms of the quantity and quality of the archaeological treasures.” The artworks date from the 8th century BC to the 3rd century BC and were displayed for journalists at the Terme di Diocleziano National Roman Museum.

The treasures were found during an investigation into the dealings of the Sicilian art dealer Gianfranco Becchina and his Swiss wife Ursula Juraschek. The pair are allegedly part of a smuggling ring that sourced antiquities from illegal excavations in southern Italy, sent them for restoration in Switzerland, and sold them around the world with forged provenance documents.

The arrest could have far-reaching implications for museums. According to Trafficking Culture, Becchina reportedly sold works to a number of illustrious institutions including the Ashmolean, the Louvre, the Boston Museum of Fine Arts, the Metropolitan Museum, the Princeton University Art Museum, the Toledo Museum of Art, and the J. Paul Getty Museum. In 2005, the Getty was forced to return three valuable looted artifacts in light of revelations about one of Becchina’s associates.

Becchina has been suspected of smuggling since 1994 when Italian police discovered a photograph of a Paestan red-figure krater by Asteas in the wreckage of a car belonging to the convicted antiquities smuggler Pasquale Camera. The Getty Museum had bought the krater from Becchina, alerting investigators that he may too be involved in illegal antiquities sales.

In 2002, Swiss and Italian police seized 140 binders containing over 13,000 documents including shipping records, invoices, and thousands of polaroid photos during a raid on Becchina’s Basel warehouse and gallery, Palladion Antique Kunst, Chasing Aphrodite reported. In 2011, he was convicted of being an important middleman in the illegal antiquities trade. He appealed the conviction, but the seizure of his archives was upheld.

According to police the charges against Becchina expired, allowing him to remain a free man. However, in the latest raids, police have secured even more documents including photos and receipts that could finally land Becchina behind bars.