The FBI believes it knows the identities of the thieves who stole art valued at up to $500 million US from Boston's Isabella Stewart Gardner Museum in 1990.

Richard DesLauriers, the FBI's special agent in charge in Boston, says the thieves belong to a criminal organization based in New England the mid-Atlantic states. He says authorities believe the art was taken to Connecticut and the Philadelphia region in the years after the theft, and offered for sale in Philadelphia about a decade ago.

The FBI has opened a new website offering a $5 million reward for information leading to return of the artworks. In a video, DesLauriers says the statute of limitations has passed for the crime of art theft and authorities are focused on recovering the art. The 13 stolen works include masterpieces by Rembrandt, Vermeer, Degas and Manet and the heist is said to be the largest property crime in U.S. history.