The FBI has seized a well-traveled forgery of a 1939 Andrew Wyeth watercolor, the fourth such counterfeit painting to surface since the artist's death in January.

U.S. Attorney David C. Weiss of Wilmington said the same fake has been offered for sale several times since 1998, even after the artist himself declared it a rank forgery.

Weiss announced the seizure yesterday with the national FBI Art Crime Team to spotlight the risks involved in buying art. Fraud and forgery are often aspects of art crime, which the FBI says is a $6 billion industry worldwide.

Weiss said the person in California who was trying to sell the painting would not be charged because he, too, had been fooled and did not know it was counterfeit.

"Unless you take these forgeries and drive a stake in them and then burn them, they keep circulating," said Ronald D. Spencer, a New York lawyer who edited a 2004 collection of essays on fake art, The Expert Versus the Object. "Stolen art always makes newspaper headlines, but it's not as prevalent a problem as forgery, because stolen art is harder to resell."

The genuine rendering of the Wyeth painting, Wreck on Doughnut Point, is worth at least $100,000. It portrays three men studying a shipwreck, images captured in the artist's familiar muted tones - in this case, brown, gray, and purple.

The forgery was offered for sale in 1998 by an auctioneer in Connecticut who sent it to Wyeth for authentication. Wyeth sent it back and informed the auctioneer that it was a fake.

Someone then sold the fake to the unwitting current owner in California for $20,000 in 2000. The California collector then offered the painting for sale last year to a Texas auction house on consignment.

To try to authenticate the painting, the auctioneer approached the Brandywine River Museum in Chadds Ford, where the painting was viewed by Wyeth collection manager Mary Landa. She instantly recognized it as the same forgery that she and Wyeth had spotted a decade earlier.

"It was indeed a watercolor and it was signed 'Andrew Wyeth,' but it was not his signature," Landa said yesterday. "It was an exact copy, with all the little squiggles, every figure in it was the same. But it was clear that it was very stiff and didn't flow like Andrew Wyeth's work."

This is one of four fake Wyeth works to surface since the artist's death at 91 in January, she said.

Worried that the counterfeit would continue to circulate, Landa contacted FBI agent Peter Gangel and Assistant U.S. Attorney David Hall, the Wilmington-based federal prosecutor who handles Art Crime Team cases nationwide.

Hall would not comment on the status of the other forgeries but said the FBI's investigation was continuing.

Federal authorities investigate art forgeries on a case-by-case basis, depending upon resources available and the significance of the fake art, Hall said.

"We want to try to nip this kind of crime in the bud because it's common for it to pick up after an artist dies and is now unable to authenticate his work," Hall said. "A prolific artist like Andrew Wyeth produced so much art that it's difficult for any one person to have a mental catalog of all his works. When collectors buy something that they think is real but is not, they undermine the legacy of the artist."

Spencer, the art forgery expert, agreed. "Fakes are most insidious for the artists themselves," he said. "After all, most of what we know about an artist comes from his work."