MILAN (AP) — The U.S. ambassador to Italy has returned to Italian officials the head of a statue stolen from an archaeological site in Rome more than 50 years ago.

Ambassador Lewis Eisenberg handed over the marble head of the mythical figure Pan to Culture Minister Dario Franceschini Thursday on the 50th anniversary of a Carabinieri unit dedicated to the recovery of cultural artifacts.

Carabinieri special investigators spotted the marble head in a California auction catalog in 2016 and notified their U.S. counterparts.

U.S. attache Armando Astorga said the piece entered the United States in the mid-2000s, after spending many years in private hands in Europe.

So far, the investigation has not determined the original thief.

U.S. Homeland Security Investigations has repatriated some 12,000 items to over 35 countries since 2007.