RACHEL MARTIN, HOST:

An update now on a notorious unsolved art heist from 1990. Late last week, federal investigators dug up an old surveillance video of the Isabella Stewart Gardner Museum in Boston. The film captures the scene before thieves made off with $500 million worth of Vermeer, Manet and a raft of Degas masterworks. The footage shows an unauthorized visitor being buzzed in by a security guard. That visitor enters through the same door from which the thieves made off with the loot the following night. They had cut the priceless canvases out of their frames. FBI investigators and the Massachusetts district attorney are asking the public to help identify the man. His shadowy face is visible two minutes into the video. The haul remains the largest art theft in American history. A quarter-century after the burglary, the 13 empty frames left in the museum that night are still on a display. Transcript provided by NPR, Copyright NPR.