“Last month, Thomas C. Bennigson, heir of the Holocaust survivor who lost control of a Picasso painting during World War II, sued Marilynn Alsdorf for $10 million, after negotiations between the parties broke down. The case has sparked claims and counterclaims regarding the painting’s history, the nature of property law and the moral obligation of art collectors and dealers. And it has pitted Alsdorf against one of the most prominent art recovery organizations in the world, the London-based Art Loss Register, which first reported that the Picasso had been looted.”