American investigators relieved some American collections of looted antique artifacts worth multi-millions of dollars and presented them to Italy. In a repatriation ceremony on Tuesday, dozens of objects — including a 4th-century sarcophagus lid in the form of a sleeping woman — went on display.

"It is my pleasure to be here today to be celebrating the return of these priceless objects to their rightful owners — the Italian people," John Phillips, the U.S. Ambassador to Italy, said during a news conference in Rome. "Italy is blessed with a rich cultural legacy and therefore cursed to suffer the pillaging of important cultural artifacts."

Over the course of several years, Homeland Security retrieved the artifacts from private collections, art dealers, and museums across the U.S. Among the pieces that museums handed over were an Etruscan Kalpis (water vessel) dating from 500 B.C., from the Toledo Museum of Art in Ohio, and a vase from the same period that the Minneapolis Institute of Arts purchased in 1983. 

In a 2012 statement from the Toledo Museum of Art, director Brian Kennedy said of the Etruscan Kalpis's return: "Based on the insurance value of the Kalpis, the Museum made a strategic decision not to pursue a legal case." He added. "As was true with the Meissen Sweetmeat Stand that was returned to Germany last year, it is part of our collections policy to deaccession and return any object for which we cannot provide clear title."

A New York gallery surrendered a Roman-era marble sarcophagus lid, sculpted in the shape of a sleeping woman. It had a price tag of more than $4 million.

The total value of the repatriated objects was not disclosed.

Officials are calling for better international controls on cross-border smuggling and thorough provenance research by buyers. Phillips told NBC News. "Sometimes it's a case of 'Don't ask, don't tell, I don't want to know.' That shouldn't be a defense."