Sometime after midnight on March 18, 1990 two men robbers dressed as policemen were buzzed into the Isabella Stewart Gardner Museum in Boston by Richard Abath, a young rock musician moonlighting as a security guard. They tied him up, as well as another guard before spending 81 minutes in the museum, making off with 13 works of art—including three Rembrandts, a Vermeer, and a Manet—worth $500 million. They also took the security footage from that night.

The largest art heist in United States' history has never been solved. The identity of the thieves was never determined, the art was never recovered, and the statute of limitations on the crime has long since passed. But now FBI investigators in Boston hope that a newly resurfaced video from the night of March 17, 1990 will help them crack the quarter-of-a-century-old case.

The 6:40 clip shows a car pull up in reverse to a side entrance at the museum. The night guard buzzes open the door and grants unauthorized access to a man at about 12:49 a.m. The man stands in the vestibule, not opening the inner door the museum, returns to his car, comes back to the entry way and then drives off. Although the authorities who released the video didn't say that it was Abath who buzzed the mystery man in, three separate officials confirmed that it was to the Boston Globe. Investigators think it could be a "dry run" for the heist the following night.

Abath, now in his 40s, was unreachable by the Globe or The New York Times. During the initial investigation, he denied any connection to the robbery but admitted that even opening the door for the supposed-policeman was against protocol, and that he allowed some friends into the museum after hours a few months before the robbery. He never mentioned having opened the side door for someone the night before the heist.

In other words: “What you see in the video does not comport with what we have been told in the past,” as Anthony Amore, the museum’s director of security, who has worked with the FBI and the U.S. Attorney’s office in a renewed push in recent years to solve the heist, told the Globe.

It's unclear if the footage was examined during the initial investigation but the prosecutor who took over the case about two years ago, Robert Fisher, pulled it from the stacks of Gardner evidence at the F.B.I. and viewed it during a "complete re-examination of the case," according to United States Attorney Carmen M. Ortiz. Now, they're making the video public in hopes that someone recognizes the mystery man and that the works of art can ultimately be recovered.

"Now we are calling on the public for help," Ortiz said.