The theft — which the FBI calls the largest property crime in U.S. history — took place in March 1990 at the Isabella Stewart Gardner Museum of Art in Boston, reports ABC News.
The thieves — who posed as policemen — managed to get away with 13 valuable paintings from the museum, including pieces by Degas, Vermeer and Rembrandt. No alarm was tripped and the criminals left through a side door, leaving only empty frames and tied up guards behind.
The FBI has put up a website about the theft. The investigators say they now know who committed the crime and have traced some of the movements of the artwork from Boston, through Connecticut and finally to Philadelphia. Investigators hope media coverage will encourage people who have seen the paintings over the years to come forward with that information.
In addition to the efforts of the FBI, the museum is offering a $5 million reward for the return of the artworks.