Twenty-three years may seem like an inordinate amount of time to solve a burglary, but the Gardner case has actually come a long way from the days when it sometimes seemed to sit on the F.B.I.’s investigative back burner — and the robbery has done a lot to change the way that museums protect their art.

Over the years, it hasn’t seemed as if federal investigators have always made the case a top priority. When I first started reporting on the theft, for instance, the museum’s director, Anne Hawley, suggested that she had not always been satisfied with the bureau’s commitment to the case. Ms. Hawley, the director since 1989, said that the first agent assigned to the case seemed very green. “Why didn’t the F.B.I. have the capacity to assign a senior-level person?” she asked me in 2007. “Why was it not considered something that needed immediate and high-level attention?”

Mr. Boser also comments on the unnamed thieves the FBI has identified in its investigation:

As for the men who robbed the museum, there’s been some good evidence over the years regarding their identities. In my book on the theft, I pointed the finger at the Boston mobster David Turner. As part of my reporting, I examined F.B.I. files that indicated that Mr. Turner was an early suspect, and he bears a strong resemblance to the composite drawing made of one of the thieves. In a letter to me, Mr. Turner denied any role in the theft, but he also told me that if I were to put his picture on my book’s cover, I would sell more copies. 

More important, there are signs that the paintings may hang on the walls of the museum again. At the news conference on Monday, the F.B.I. announced that in the years after the theft, someone took the stolen Gardner art to Connecticut and Philadelphia and offered it up for sale. This suggests that the canvases might still be in good condition.

On the 20th anniversary of the theft of the ISGM, NPR's "On Point" Tom Ashbrook interviewed Anne Hawley, Director of the Isabella Stewart Gardner Museum, and Anthony Amore, Director of Security. Amore, an ARCA Trustee, takes Ashbrook down to the basement to where the  museum's two security guards were handcuffed and duct-taped during the robbery.