After 20 yearsand thousands of leadsinvestigators might finally be on the brink of solving the largest art theft in history.

>>Gallery: The Stolen Paintings

The wee hours of March 18, 1990, were good ones for a robbery. Most of Boston was still out celebrating Saint Patrick’s Day with boozy cheer. A light rain had fallen earlier in the day. The streets of the Fenway were wet and slick. Shortly after midnight, two thieves dressed as police officers approached the Palace Road side entrance of the Isabella Stewart Gardner Museum.

The institution is one of New England’s most beautifully romantic spots, a treasure palace brimming with masterpieces by Botticelli, Velázquez and Rubens. Through an intercom, the thieves told the night guards they were investigating a disturbance. The fake cops were buzzed into the building, and they quickly thrust the security guards against a wall.

“This is a robbery,” one of the thieves said. “Don’t give us any problems, and you won’t get hurt.” “Don’t worry,” a guard muttered, “they don’t pay me enough to get hurt.” The crooks wrapped strip after strip of duct tape around the eyes and mouths of the guards, swaddling their heads until they looked like mummies.

They brought the guards into the basement of the museum and handcuffed one to a pipe and the other to a workbench. The thieves then strode through the galleries. They owned the museum for the night, and they looted the galleries for over an hour, stealing more than a dozen artworks including one Vermeer, three Rembrandts and five Degas. It was the largest art heist in history and the biggest burglary in American memory. Today, experts believe that the stolen paintings are worth as much as $500 million.

It has been more than two decades since the Gardner theft, and despite dozens of investigators, thousands of leads and a $5 million reward, not a single artwork has been recovered, not a single arrest made. But over the past few years, it appears that the caper might finally be breaking open, and new evidence about the crime has been making headlines around the country. Or as Anthony Amore, the museum’s current director of security, told me recently: “I have no doubt that the art will again be displayed.”

The Gardner theft has long inspired obsession. Some art hunters want the $5 million reward, one of the largest ever offered by a private institution. Some are fascinated by the lost pieces, and novels, movies, poems, drawings and paintings have all been dedicated to the caper. “Think of how bored they get, stacked in the warehouse somewhere, say in Mattapan, gazing at the back of the butcher paper they are wrapped in, instead of at the rapt, glad faces of those who love art,” wrote novelist John Updike of the stolen paintings.  

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