An unsolved murder in 1991 is being revisited by authorities for possible clues about the infamous art heist at Boston s Isabella Stewart Gardner Museum, reports Bob Ward for Boston 25 News. In the over three decades since thieves made off with treasured artworks valued then at $500 million, including a rare Vermeer and Rembrandt s only seascape, investigators have looked into the security guards, New England crime figures and others as culprits. The March 1990 heist of 13 still-missing .