A massive collection of Nazi-looted paintings discovered last year in a Munich apartment includes works that art historians previously thought were destroyed and some other works that scholars didn’t know existed.

Earlier this week, Germany’s Focus magazine reported that in the spring of 2011, authorities discovered more than 1,400 paintings in the home of Cornelius Gurlitt, whom they were investigating for tax evasion (the magazine later corrected the date after the German government said that the seizure occurred in the winter of 2012). Gurlitt, the son of an art dealer, has been described as a recluse who made his living by occasionally selling the paintings at auction. During the 1930s and early 1940s, Gurlitt’s father Hildebrandt helped the Nazis sell artworks seized from Jewish families, and the discovery of his son’s art trove has led to questions about whether these works were also plundered during that time.

Early reports said that the collection contained works by masters such as Henri Matisse, Pablo Picasso and Marc Chagall. Art historian and investigator Meike Hoffmann showed slides of some of the paintings at a news conference on Tuesday. “It is a very emotional thing to see that all these works of art still exist and were not destroyed,” Hoffman told the BBC.

“You could conceivably set up a museum with this lot,” BBC arts editor Will Gompertz wrote. “Art historians all over the world will be preparing to rewrite biographies of several modern artists.” Among the 121 framed pieces and 1,285 unframed works that have been catalogued, experts have discovered previously unregistered works by Chagall, Matisse and Otto Dix. Add in works by artists such as Picasso and Gustave Courbet, and the collection is believed to be worth roughly 1 billion Euros ($1.35 billion). A customs spokesman told Focus that the artwork was stacked behind piles of old food tins and other junk in Gurlitt’s apartment.

Since details of the trove have come to light, questions have swirled about how Gurlitt managed to keep the collection a secret and why the German authorities took so long to reveal it had been seized. The discovery also pushed the legacy of Nazi war crimes back into the news. Experts estimate that more than 16,000 pieces of art were looted from Jewish homes by the Nazis during the Holocaust. “We know that from all the cases we have, that we’re trying to find…that 90 percent are still missing,” Ann Webber of the Commission for Art Looted in Europe told the BBC. “When I say ‘missing,’ some of them are in collections like this, and some of them are in museums that haven’t published what they have.”

Authorities now have to determine which pieces found in Gurlitt’s apartment were looted and how families can make claims, but those expecting some kind of criminal action will be disappointed. Augsburg’s chief prosecutor Reinhard Nemetz said that Gurlitt cooperated with authorities. There is no warrant for his arrest, and since he officially resides in Austria, German authorities say his whereabouts are unknown.