The FBI says the two men it suspects masqueraded as police officers to rob a Boston art museum of $US500 million ($A680.92 million) worth of masterpieces in 1990 are dead.
Two years ago, investigators announced they knew who stole the 13 works - including paintings by Rembrandt and Vermeer - from Boston's Isabella Stewart Gardner Museum. They refused to elaborate, saying only that the investigation was now focused on recovering the missing artwork.
But Peter Kowenhoven, the FBI's assistant special agent in charge in Boston, tells The Associated Press the thieves are deceased.
Kowenhoven declined to identify the suspects.
On Thursday, authorities released grainy surveillance video from the eve of the heist and appealed anew to the public for help in finding the artworks.
