Federal investigators in Boston released 25-year-old surveillance video showing a security guard letting a man into the Isabella Stewart Gardner Museum, the night before it was robbed of $500m (£322m) worth of art in the largest such heist in US history.

The seven-minute video shows a young white man with a short jacket being let in by the guard through a rear entrance to the museum shortly after midnight on 17 March 1990, about 24 hours before the heist.

The statute of limitations on the crime has long passed, meaning that if the thieves are found they will not face prosecution. But the FBI, the Boston office of the Justice Department and the museum hope to recover the art.

"Today we are releasing video images from the night before the theft – images which have not previously been seen by the public – with the hope of identifying an unauthorized visitor to the museum. With the public's help, we may be able to develop new information that could lead to the recovery of these invaluable works of art," US Attorney Carmen Ortiz said in a statement.

The newly released grainy video shows a car pulling up to the museum that matches the description of a vehicle spotted outside shortly before the heist. The theft occurred when two men dressed as police officers were admitted by security guards to the museum in the early morning hours of 18 March. They went on to overpower the guards who were found duct-taped to chairs in the museum's basement the next morning.

Works of art including Rembrandt's Storm on the Sea of Galilee, Vermeer's The Concert and Manet's Chez Tortoni, were among the 13 pieces stolen from the museum, which features the collection of the eccentric Boston socialite Gardner.

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