Isabella Stewart Gardner Museum in Boston, Mass.
Isabella Stewart Gardner Museum in Boston, Mass. - 

It was 23 years ago today that thieves dressed as police officers walked out of Boston's Isabella Stewart Gardner Museum with half a billion dollars of art, including works by Degas and Rembrandt, tucked under their arms.

It's widely regarded as one of history's biggest art heists. And I mention it because today the FBI said in a press conference they know who did it. But they're not gonna tell us.

The FBI does say they think at least part of the haul was fenced in Philadelphia, but that the statute of limitations has run out for the original thieves.

The FBI is still offering a $5 million reward for information that leads to recovery of the art.

Follow Kai Ryssdal at @kairyssdal