27 years later, a museum is offering $10 million for help solving the biggest art heist of all time

• The 1990 Isabelle Stewart Gardner Museum theft is the biggest art theft of all time.
• Until December 31, the museum is offering a $10 million reward for information that helps them recover the lost paintings.
• The trail has been cold for years.

In 1990, a pair of thieves dressed as policemen walked out of a Boston museum with $500 million worth of art.

No one has seen them since.

The Isabella Stewart Gardner Museum heist is the biggest art theft of all time. And it remains unsolved. The museum is offering $10 million for information that can help recover the lost paintings.

But the clock is running out. The museum's $10 million offer ends in December. It's a temporary increase, set in May, from the museum's longstanding $5 million offer.

"It’s conceivable that some criminal organization or people might be wishy-washy about the $5 million," Anthony Amore, the museum's director of security, told the New York Times. "But it’s not conceivable that they're feeling the same way about the $10 million."

The heist is as famous for its brazenness as it is for its value. It was carried out over just 81 minutes, shortly after midnight on March 18, 1990. The two thieves handcuffed the museum's two security guards in the basement and walked out with 13 pieces of artwork. They include "The Concert," one of Vermeer's 34 known works, and Rembrandt's only known seascape, "The Storm on the Sea of Galilee," as well as two of his other paintings.

Today, empty frames stand where those paintings once were.

In 2013, the FBI announced it knew the identities of the two thieves — but that they were both dead. They're thought to have passed on the paintings to connections in Northeastern mob circles.

There's no established reason for why the artwork was stolen — none of it seems to have appeared on the black market — but numerous theories have emerged over the years. One mob associate may have stolen it in order to collect reward money upon its return — but was caught by an unrelated FBI sting and left the artwork to gather dust. In another theory, mobsters connected with the IRA stole the painting to help fund the army's operations.

But the museum is still hoping for their return.

"I’ve spent more than a decade preparing for any scenario," Amore told the Times. "I’m very ready. I’ll go anywhere. I’ll meet with the devil for these paintings."

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