The FBI said there is new hope that the case of one of the most audacious -- and expensive -- art heists in history could be solved, but more than two decades after the crime there remain empty frames where $500 million-worth of art should be.
In a stunning development, the FBI announced Monday the bureau has identified, but not apprehended, suspects they believe were involved in the infamous theft of 13 masterpieces from Boston's Isabella Stewart Gardner Museum of Art 23 years ago.
Making Off With $500M in 81 Minutes
In March 1990 just about all of Boston was celebrating a long St. Patrick's Day weekend, save for a pair of thieves and some unsuspecting museum guards, who were about to find themselves in the middle of what the FBI calls the "largest property crime in U.S. history."
Just after 1 a.m., with parties still going on downtown, two thieves dressed as policemen talked their way into the side entrance of the tiny Isabella Stewart Gardner Museum of Art.
The thieves managed to tie up the security guards and then they methodically went through the museum, cutting 13 pieces from their frames, including works by Rembrandt, Degas and Vermeer. There were no alarms and after 81 minutes, the thieves walked out the door with an estimated $500 million-worth of art.
In the more than two decades since, the museum left the frames on the walls empty, as a reminder of the crime.
The statute of limitations on prosecuting the thieves has long passed, but officials at the FBI and the museum have not given up hope in recovering the paintings. They are hoping a $5 million reward offered by the museum and a new FBI website dedicated to the theft could help.
Gardner museum security director Anthony Amore told ABC News he is "heartened" by the latest developments in the case.
"I really believe these efforts are going to return these paintings to us and we'll be made whole again," said Amore, author of the art heist book "Stealing Rembrandts." "It's incredibly important to me that this story stay alive... To describe the significance of these paintings... It's a level of master work we talk about. We'd have to imagine our favorite book or play. It's like losing Hamlet."
Despite the estimated value of $500 million for the works on the legitimate market, they are so well known in the art world that the FBI and art experts figure they actually have very little value for the thieves -- too hot to handle, even now, 23 years later.
As one agent put it, they are worthless other than back on the walls of the Gardner museum.
ABC News' Alyssa Newcomb contributed to this report.