Officials now faced a daunting challenge: to identify the art, determine its legal situation and find the rightful owners of the works, many of which may have been seized by the Nazi regime.
So far, officials said they have done at least preliminary research on only about 500 of the pieces.
The apartment in an upscale Munich district was searched in February 2012 as part of a tax investigation that started with a random check by customs officers on passengers taking a Zurich-Munich train in late 2010.
Prosecutors said the check aroused their suspicions enough to launch a preliminary tax probe against one man. They wouldn't give further details, citing tax secrecy laws and the ongoing investigation. No charges have been filed. Germany has been on the hunt for tax cheats for several years after stolen bank records showed that thousands of German citizens had bank accounts in Switzerland.
The 121 framed and 1,285 unframed paintings were found in one room at the apartment, where they were "professionally stored and in a very good condition," said Siegfried Kloeble, head of the customs investigations office in Munich. He said it took a specialist company three days to remove the paintings from the apartment; officials refused to specify where they are being kept.
Prosecutors are now probing whether the works were improperly acquired by the suspect, who they said hasn't asked for them back. They did not identify him and said they are not currently in contact with the collector.
The collection includes works by 20th-century masters such as Pablo Picasso, Max Liebermann and Ernst Ludwig Kirchner and earlier works by artists including Henri de Toulouse-Lautrec, Gustave Courbet, Auguste Renoir and Canaletto. It also features work as old as an etching of Christ's Crucifixion by 16th —century German master Albrecht Duerer.
It's unclear how many of the works might be subject to return to pre-World War II owners.
Prosecutor Reinhard Nemetz told reporters in the Bavarian city of Augsburg that investigators have turned up "concrete evidence" the find includes both works that Nazis classed as "degenerate art" and seized from German museums in 1937 or shortly after, and other works that may have been taken from individuals. The Nazis often forced Jewish collectors to sell their art at pitifully low prices to German dealers or simply took them.
"Degenerate art" was largely modern or abstract works that the regime of Adolf Hitler believed to be a corruption influence on the German people. Many such works were later sold to enrich the regime. An art expert working with prosecutors said those sales are legally valid, even if other works in the collection may eventually be found to belong to survivors of Nazi persecution or their heirs.
Art historian Meike Hoffmann, an expert on "degenerate art" at the Free University of Berlin, offered a glimpse of some of the works during a slide show at Tuesday's news conference with prosecutors.
She showed works she said had not been known to scholars, or known only from documents without any extant photos to give an idea what the work looked like.
"Such cases are of high importance to art historians," she said.
A painting of a woman by Henri Matisse that was confiscated by the Nazis in France during World War II is not in the established catalog of his works, she said.
A Chagall gouache of an allegorical scene also isn't among the artists' listed works. Works such as an unknown self-portrait by 20th-Century German artist Otto Dix and a woodcut by Ernst Ludwig Kirchner add new breadth to what's known about them, Hoffmann said.
Hoffmann, an expert on the German expressionist movement that Kirchner belonged to, said the woodcut gave new insight into the artist's use of color.
Experts haven't yet been able to determine where the Chagall came from, she said, describing the research as "very, very difficult."
"When you stand in front of the works, see the ones that were long thought to have been lost or destroyed and in a relatively good state — some of them dirty but not damaged — you have an incredible feeling of happiness," Hoffmann said.
Some 500 works have undergone at least preliminary examination. Some correspond to known works that appear to have been legally sold, although their recent whereabouts may have been unknown.
For instance, a work by Courbet, previously in lists of his work, of a girl with a goat was found to have made its way into the collection through an auction in 1949 — after the end of World War II. A Franz Marc work, "Landscape with Horses," was identified as coming from an art museum in Moritzburg, Germany.
Nemetz defended the delay in making the find public. He rejected calls to make images available on the Internet to help potential owners, citing copyright and security concerns.
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