As a professor studying art crime, I keep a close eye on online sales of antiquities. I was especially worried three years ago when I spotted a listing for an ancient Assyrian sculpture on the website of the New York City-based Sadigh Gallery. These magnificent sculptures from Iraq are so rare that scholars like me know each and every example. But here was one I’d never seen before.

The gallery’s listing did not mention that the sculpture had the extensive paper trail needed to prove it had left Iraq legally. I thought that it must have been recently looted. In war-torn Iraq, looters have been busy destroying the past and smuggling out stolen cultural heritage to sell to foreign collectors. The profits from this looting sometimes fund militant groups — putting Iraq’s future as well as its past in danger. How had one of these precious artifacts ended up for sale a few blocks away from the Empire State Building?

But once I zoomed in on the website’s pictures, I stopped worrying that the sculpture had been ripped from an Iraqi archaeological site. Beneath various ancient-looking encrustations stuck to the stone, the carving of a winged man was crude. Genuine Assyrian sculptures are minutely detailed and realistic. But the feathers on this sculpture only had a few lines, as if the carver’s arm had gotten tired, and the figure’s toes end in bizarre wavy lines. It was a fake.

This month, the Manhattan district attorney’s office found that this sculpture was far from the only fake for sale at the Sadigh Gallery. Investigators say they found thousands of fake antiquities in the gallery’s back rooms, along with the belt sander used to distress objects strategically and mudlike putties used to make them look like they had spent millennia underground. The DA’s office said the gallery’s owner, Mehrdad Sadigh, appeared to be one the biggest sellers of fake antiquities in America.

Some of these fakes went for tens of thousands of dollars. One of the most bizarre was an ancient Egyptian “body part” — a supposedly mummified erect penis, complete with testicles — for a mere $15,000. But most of the gallery’s items were, as their advertisements put it, sold for “wholesale prices.” For a hundred dollars or so, you could have purchased what you thought was a piece of the past from Egypt, Iraq, Syria, Afghanistan, Nepal, India or Central America — all places trying desperately to fight the looting of archeological sites.

So why should we care about the busting of a forger when real antiquities are under threat? Because every sale of a fake antiquity encourages the black market in looted heritage. If you buy an artifact without knowing exactly where it came from, when it left its country of origin, and how it entered the United States, you aren’t asking enough questions. You might be fooled into buying a tourist figurine someone has dipped into spackle...or you might be participating in a black market that steals our global heritage.