NEW YORK.- Brian Ross and Jill Rackmill of the ABCNEWS reported that two Polaroid photos in a plain envelope with no return address arrived by mail at their office in New York which could provide clues into a heist the FBI calls the largest art theft in American history. The postage-sized etching was acquired in 1896 and stolen from the Dutch Room of the Isabella Stewart Gardner Museum in 1990.  To verify the date the alleged Rembrandt was placed atop of a Boston Globe front page. The photo could be an elaborate hoax, said ABCNEWS, but, if authentic, it could prove that the Rembrandt still exists and could be an important clue in a case that for 14 years, the FBI has been unable to break.

ABCNEWS reported that they learned of a secret 1997 meeting between a one-time member of an art theft ring and museum officials after a seven-year investigation into this case, and that a new deal with the FBI may be in the works.

The 1990 break-in led to an international search for the 12 masterpieces, including works by Rembrandt, Vermeer, Degas and others, which are likely worth as much as a half-billion dollars, according to the museum and the FBI. "To have art of that quality taken and never to be seen, never to be appreciated by anybody again, is a devastating impact on the city and frankly, on the art world," said Donald Stern, the former U.S. attorney for Massachusetts.

Despite a $5 million reward, the art is still missing and law enforcement is no closer to making an arrest. To date William P. Youngworth III, a one time member of a notorious art theft ring, has been a crucial figure in to possible locating the stolen masterpieces.

"I believe I have a very accurate picture of everything that’s transpired," Youngworth told ABCNEWS and later said that he is not willing to cooperate with the FBI. "Do you want to put somebody in a cell, or do you want the art back?"

Within days of the theft, Youngworth became and remains a focus of the FBI investigation, even though he has about the best alibi possible for his whereabouts that night: He was in federal prison in Memphis, Tenn., for failing to appear in court and for committing an offense while on release. He couldn’t have stolen the paintings. Now free, for the last seven years, Youngworth has been in a high-stakes battle of wits with the FBI and federal prosecutors, trying to prove that he can get the art back without giving the FBI enough proof to put him in prison for possession of stolen property.

When asked if he has seen the paintings since they were stolen, he replied, "Of course not," with a coy expression.