This week Spanish police announced that seventy-five people across Europe have been arrested as part of an investigation into illegal art and antiquities trafficking. The investigation involved collaboration between Interpol, Europol (the European policing agency), and UNESCO as well as the cooperation of law enforcement in (among other countries) Austria, Belgium, Bulgaria, Germany, Greece, Malta, the Netherlands, Poland, Portugal, Spain, and Switzerland.

The arrests that resulted from Operation Pandora (the investigation’s code-name) were made last November, but only announced this week. While a full inventory of recovered items has not been released to the public, Spanish police reported that in the city of Murcia they recovered about 500 archeological artifacts, including nineteen that had been stolen from the city’s archeological museum in 2014. Europol is reporting that, in total, 3561, have been recovered and ninety-two new investigations have been initiated as part of the operation.

Among the items retrieved as part of operation Pandora were several of greater archeological significance. In Greece, the Hellenic police retrieved a marble Ottoman and tombstone, a post-Byzantine icon of St. George, and two Byzantine era artifacts. But there are plenty of other important artifacts that have yet to be returned to their home countries and while many of them are lost others are on display in foreign museums.

1. Dove with Green Peas

In 2010 a lone hooded thief managed to climb into Paris’s Museum of Modern Art. The alarms did not sound when he entered the building and he was about to steal five priceless works right out of their frames. Among them was Dove with Green Peas by Pablo Picasso, Pastoral by Henri Matisse, Olive Tree near l’Estaque by Georges Braque, Woman with Fan by Amedeo Modigliani, and Still life with Candlestick by Fernand Leger. The heist, which reminded commentators of the Pink Panther movies, was valued at between 100-200 million euros.

More than a year later three men were placed under official investigation. According to his story the five masterpieces ended up crushed by a garbage truck. Even though two men were convicted in the case, no evidence of the artwork was never discovered. One of the alleged accomplices, a 34 year-old watchmaker, told the French police that he had panicked and thrown the canvasses into a trash container. Police were skeptical of his story. It’s possible that the art was thrown out like common trash, or someone out there still has the art on very private display.

While there are many prominent art thefts out there, the Art Loss Registry in London said that this was “one of the biggest art heists ever, considering the estimated value, the prominence of the artists and the high profile of the museum.”

2. Nazi Artwork

It wouldn’t be a listicle about stolen artifacts if we didn’t mention the Nazis. There’s no end to the stories of gold, artwork, and other valuables they stole from prominent Jewish families during World War II.

What’s less known is how the art was effectively returned to Nazi-families in the 1950s and 60s. In the years that followed the end of the war American officials returned more than 10,000 pieces of art to the Bavarian authorities with the intent that they be returned to the families from which they had been plundered. For example, as a New York Times story revealed, Hitler’s private secretary, Henriette von Schirach, and her family effectively lobbied the Bavarian State to return nearly 300 pieces of art to them at a discounted rate. Among them was a small painting, “View of a Dutch Square,” by Jan van der Heyden. The landscape had originally been owned by the Kraus family, a Jewish family who had fled Vienna in the war and whose art collection was seized by the Gestapo in 1941. Rather than return the painting to the Kraus’s descendants it was sold to von Schirach for 300 Deutschmarks (approximately $75 at the time). A subsequent investigation by the Krauses great-grandson, John Graykowski and the Commission for Looted Art in Europe, revealed that hundreds of pieces of art were resold to Nazi-tied families for a small fraction of their worth.

3. Priam’s Treasure

Even if the Nazis were the most precocious looters of artwork in the twentieth century, they received a taste of their own medicine at the end of World War II. In 1837 German classical archeologist Heinrich Schliemann discovered a horde of gold and copper ancient weapons in Anatolia (modern Turkey). Among the artifacts were 8,750 gold rings, buttons, and other small gold objects. Schliemann was convinced that he had found the ancient city of Troy and named his discovery after the city’s ill-fated king. Schliemann smuggled the cache to Berlin, their removal only being discovered when Schliemann’s wife, Sophia, audaciously wore the jewels for the public. The Ottoman official who had been assigned to oversee the dig was imprisoned and Schliemann returned some of the treasure in exchange for permission to excavate at ‘Troy’ again. The rest of the hoard was exhibited at the Royal Museums of Berlin.

But in 1945 Priam’s Treasure disappeared out of a bunker under the Berlin Zoo. The Soviet Government, whose Red Army was known to have stormed the city denied an knowledge of the whereabouts of the gold. That is until 1993, when the treasure went on display at the Pushkin Museum in Moscow. Technically speaking the Russians are obligated to return the treasure, but they are currently refusing to do so. The directors of the Pushkin claim that they are keeping the treasure as part of reparations owed to them by the German government.

4. Lioness Attacking a Nubian

As the city of Baghdad fell to coalition forces in 2003, reports began to emerge that the National Museum of Iraq, home to arguably the world’s finest collection of Ancient Near Eastern artifacts, had been repeatedly looted. Initial reports stated that 170,000 items had been stolen, but these numbers were later shown to have been greatly inflated. As the smoked cleared it emerged that the tally was closer to between 10,000 and 15,000 pieces and not every looter knew what they were doing. There were professional looters who cherry picked the most prized treasures, random looters who stole mostly excavation site pieces but also ended up lifting worthless replicas intended for the gift-shop, and there were insiders who focused on jewelry and cylinder seals. A stellar investigation by US Lt-Col Matthew Bogdanos led to the return of many items but a number, including the huge collection of cylinder seals, remain missing.

Still missing though is “Lioness attacking a Nubian” a remarkable eighth-century BCE ivory plaque. It is set with lapis lazuli (one of the Bible’s most precious jewels) and carnelian and overlaid with gold. There are two similar plaques in existence and both of them are currently housed in the British Museum. Other prestigious items from the collection like the Warka Head were stolen and returned and others still like the Golden Lyre of Ur (one of the oldest stringed instruments in the world) was hidden from thieves and damaged by flooding. A complete list of items still missing from 2003 can be found on a University of Chicago Oriental Institute website.

5. The Wiener Collection

In December 2016, New York art collector and antiquities dealer Nancy Wiener was arrested for smuggling, laundering, and arranging the sale of plundered Asian art . Her prestigious Upper East Side gallery has sold art to private collectors and also to important public collections like the Art Institute of Chicago and the Metropolitan Museum of Art. According to the complaint against her, Wiener purchased antiquities from thieves, had them restored in order to erase the evidence that they had been looted (for example modern saw marks are a clear sign of recent interference), and then laundered through Sotheby’s and Christie’s. Part of her strategy, it is alleged, was to create a false paper trail of owners in order to falsify the provenance (legal chain of ownership) to a period before 1972, when UNESCO regulations about antiquities began to be implemented.

The investigation into Wiener and the identification of trafficked items that have passed through her galleries owes a great debt to the remarkable work

of James Felch, author of the antiquities trafficking blog Chasing Aphrodite. Felch was instrumental in exposing the illegal origins of many items in the Getty collection and is the co-author, with Ralph Frammolino, of the book Chasing Aphrodite. In just the past few weeks Felch and his readers have identified a number of pieces of doubtful provenance. Victoria Reed, a curator at the Boston Museum of Fine Arts, shared details of five items in their collection about which she was concerned. These include an exquisite tenth century CE Sandstone sculpture of Shiva Lord of the Dance from Central-eastern Madhya Pradesh. Wiener sold the sculpture to the museum in 1992 and it has no known provenance.

How did Wiener get away with this for so long? In part because she was a second-generation ‘trusted dealer’ and buyers and immigration authorities never fact-checked her paper trail. If they had, they likely would have realized that many of the ‘owners’ of the items she was selling were fictitious.

Operation Pandora focused on criminal networks and on antiquities trafficking that involved cultural spoliation (this is trafficking that involves forcible removable of antiquities, especially from war-torn areas), but the most revealing and troubling thing about antiquities trafficking is just how far and high it goes. Illegal art and antiquities trafficking extends from terrorist groups like ISIS, plundering local archeological sites to fund their obscene war; to criminal networks and art thieves trying to turn a tidy profit; to governments who protest that plundered artifacts are just reparations; to museums, art galleries, and even royalty who claim either that they are rescuing artifacts or that time has effaced the negative circumstances under which they acquired their artifact. From the most universally hated element of our global society to the most elite and respected institutions many people have their fingers in the antiquities pie.

If we are outraged by ISIS (and we are), we should be similarly concerned by those willing to smuggle and purchase plundered artifacts and those hesitant to return them to their rightful owners. And we really, really have to check their paperwork.