THE BURNED OVER DISTRICT

The Nazi leadership, lead by Herman Goering, loved to collect art and with their conquest of Europe vast amounts of artwork became "available". Some was "bought" at ridiculous prices and some was simply appropriated and with murderous efficiency of the Nazi camp system, many owners and their families were eliminated. As a result many works of fine art ended up in somewhere else, in private collections that remained unexamined unless the current owners chose otherwise.

After World War II, few Germans with sizable art holdings made a point of digging into their collections for signs of Nazi looting.

And because private collections were off limits for those trying to track down stolen art, works of unexamined provenance have hung for decades in family homes and office corridors, the stories of how they were acquired often vague, inconsistent or simply not discussed.

But as one generation of Germans has died and given its art to the next, a number of people with prominent collections and unsettled consciences have stepped forward to investigate what they own.

“I don’t want stolen goods hanging on the wall — it’s quite simple,” said Jan Philipp Reemtsma, who hired a researcher 15 years ago to examine the collection he inherited from his father, the tobacco industrialist Philipp F. Reemtsma.

Now, to persuade more collectors to undertake such research, the German government has announced it will begin subsidizing such efforts, using money from a national fund of 3.4 million euros (about $3.6 million).

Until now, public money had helped to search for looted items only in German museums and libraries. The decision in February to broaden the scope was made after the 2013 revelation of Cornelius Gurlitt’s art hoard in his Munich apartment.

Mr. Gurlitt had inherited the art from his father, a dealer for the Nazis who purchased works that had been seized from Jewish households or sold under duress by Jews desperate to flee. The case brought the issue of tainted art in private collections to the fore, raising the specter that thousands of plundered artworks might be lurking in attics and cellars.

The German government team studying the Gurlitt works has identified five that were looted or sold under duress, and another 153 that it suspects were looted.

Mr. Hartmann said in recent years that he had seen an uptick in interest by private collectors who want to understand the origins of their art. He estimates reviews of a dozen collections are underway or have been completed. His office had long received the occasional package in the mail, containing an object the sender assumed was stolen, he said. Since the Gurlitt case, the parcels are more frequent, he said.

So a younger and more socially conscious generation is asking the questions their parents didn't or if they did chose to ignore. But with the passing of time, finding the true story and the true owners becomes more difficult. And what is to be done about works that are known to have been stolen but no previous owners or heirs can be found?