"This week marks the 30th anniversary of the world’s largest unsolved art theft, in which 13 pieces worth around $500 million, including paintings by famous artists such as Rembrandt, Vermeer, Degas and Manet, were stolen from the Isabella Stewart Gardner Museum in Boston.
"The staggeringly high value of the theft, for which nobody has been held criminally responsible, puts it in contention as the single largest theft of private property in the modern world.
"There remains a record $10 million reward for information leading to the return of the artworks."
Short article at Scottish Legal (law): Link
Six theories at the Boston Globe: Link
The Reward: Link
At Wiki: Link