When police entered the small house in Berwyn in 2007, they were greeted by an astonishing sight: hundreds of boxes filled with such items as letters written by kings, Vatican documents penned by Catholic popes, even a handwritten book preface by Benito Mussolini. In all, there were about 3,500 ancient artifacts, religious relics, rare manuscripts, and other historic items,1,600 of which had been stolen from Italy and shipped to the U.S. to be sold.

The 1,600 items, which the late John Sisto had collected, will be returned to Italy later this week, the FBI says. Estimated value is up to $10 million. Sisto's father, Giuseppe, would travel to Europe and ostensibly buy the items in estate sales, then ship them overseas for his son to sell. But John’s son Joseph, who contacted local police after his father died, said his father had become attached to the items and kept them. After their discovery, Berwyn police contacted the FBI’s art crimes unit, which launched a two-year investigation into which items had been stolen. The inquiry found that nearly half the items had been purloined.