Retired FBI agent Robert Wittman at home. He often worked undercover, so his face remains unphotographed.

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Heritage Auction Galleries has been presenting a monthly lecture series in Dallas. The speakers have included experts on collecting antique silver or how to preserve artworks. This month’s speaker is a little different. He’s a former undercover FBI agent.

Robert Wittman worked for 20 years at the FBI investigating art thefts, forgeries and the illicit trade in antiquities. But it’s only been since 2004 that the bureau has even had a National Art Crime Team. Before that, Wittman says, he was pretty much alone.

WITTMAN: “But as a result of the looting from the Baghdad museum in 2004 and 2003, the FBI realized that this was a worldwide problem. So I started the Art Crime Team. And it’s been very successful. The team has recovered more than $130 million worth of art and artifacts.”

Armed thieves make off with two Edvard Munch paintings, including the famous “Scream,” in Oslo, August 2004

Wittman has been one of the world’s top stolen art investigators. He helped recover a stolen copy of the Bill of Rights and a self-portrait by Rembrandt. His undercover exploits have been written up in the Wall Street Journal and the London Times.

But even with the 12-member Art Crime Team, the U. S. seriously lags behind Europe when it comes to specialized art squads. Italy has more than 200 agents working on art security, France has 35. The international art trade is a $200 billion industry, Wittman says, and the FBI estimates that $6 billion of that is illegal. It’s true that the U. S. has not seen the stunning daylight thefts that Europe has the past decade. These have often been armed robberies, and they’ve made away with masterpieces by Renoir, Edvard Munch, even an enormous bronze sculpture by Henry Moore. Yet the largest single heist in the world – the theft of 13 paintings – happened in Boston and it remains unsolved after 18 years.

Six weeks ago, Wittman retired from the FBI. He’s now a security consultant to museums and insurance companies. Which is the point of his public lecture Tuesday at the Heritage Auction Annex as part of its 2nd Tuesdays @ Slocum literary series. He advises people on how to avoid being defrauded and how to protect the artworks they do have. So if anyone has a few Cezannes hanging around, he has this basic piece of advice:

WITTMAN: “Take good photographs — because if we can’t identify what’s been taken, we can’t recover them. You can’t tell which is which. So we need good photographs.”