It was the biggest property crime in U-S history — the art heist at Boston’s Isabella Stewart Gardner museum.

Now,art  theft experts say because  authorities think they know who stole the rare art –  the chances of getting the paintings back are good.

The FBI won’t disclose the identities of the thieves the agency thinks posed as police officers in 1990 and made off with  13 pieces including paintings by  Rembrandt, Vermeer and Manet worth as much as $500 million.

F-B-I Special Agent Rick DesLauriers believes  the thieves were members of organized crime and transported the works to Philadelphia and Connecticut over the years.

The museum is offering a five million dollar reward.

Christopher Marinello is a lawyer who recently recovered a Matisse painting stolen from a museum in Stockholm in 1987.    He says 23 years is not an unusually long period of time when it comes to recovering rare stolen art.

Marinello says he believes someone will expose someone else to claim the $5 million reward.