This drawing by Carl Spitzweg was seized in 1939 from Jewish music publisher Heinri Hinrichsen, who was killed at the Auschwitz death camp in 1942. It was acquired by Nazi art dealer Hildebrand Gurlitt — and later found among the spectacular collection of works hoarded by his son, Cornelius Gurlitt. The work was auctioned by Christie's at the request of Hinrichsen's heirs.

The watercolor by the Jewish painter Max Beckmann entered Gurlitt's collection only in 1945. Held by the allied occupation forces at the Central Collecting Point in Wiesbaden from 1945-1950, it was returned to Hildebrand Gurlitt in 1950. Before working for the Nazi regime, Gurlitt had collected and exhibited modern art, curating Beckmann's last exhibition in 1936 before the artist fled Germany.

This work was owned by lawyer and art collector Fritz Salo Glaser. Artists of Dresden's avant-garde scene were his guests in the 1920s — as was the young Hildebrand Gurlitt. It is not known how Gurlitt came to possess the painting. It was confiscated in 1945 and later returned. Of Jewish heritage, Glaser only narrowly avoided deportation to the Theresienstadt concentration camp in 1945.

This painting by the famous impressionist is not suspected to have been looted. The artist sold it to the Durand Ruel Gallery in 1907. The Jewish art merchant and publisher Paul Cassirer is said to have given it to Marie Gurlitt as a present, and she left it to her son Hildebrand Gurlitt in 1923.

A short handwritten note allowed provenance researchers to identify this work by the French painter as a looted work of art. The picture was seized from the collection of Jewish politician and resistance leader Georges Mandel, who was executed by French fascists near Paris in 1944. German Culture Minister Monika Grütters (right) handed over the work to Mandel's heirs in January 2019.

The activist group Provenance Research Gurlitt identified this painting by French neo-impressionist Paul Signac as stolen Jewish property in October 2018. Gaston Prosper Levy fled Nazi-occupied France in 1940. Occupying soldiers are believed to have looted his art collection shortly before his escape. The painting was returned to Levy's family in 2019.

Hildebrand Gurlitt must have acquired this work by the French sculptor between 1940 and 1945. Previously belonging to the Frenchman Eugene Rudier, it entered circulation in 1919 at an auction by Octave Henri Marie Mirbeau, who is said to have received it as a present from the artist.

This copper engraving by Albrecht Dürer once belonged to the Falkeisen-Huber Gallery in Basel. It is not known how it got there or how long it was there however. In 2012 the engraving turned up in Cornelius Gurlitt's collection. "Old masters" like Dürer were very important to the National Socialists' view of art and were often exploited for propaganda.

The provenance of this drawing is completely unknown. It is certain, however, that Hitler considered Norwegian artist Edvard Munch's work "degenerate art." Some 82 pieces by Munch were confiscated in German museums in 1937.

Hitler venerated 18th-century French painting. He secured exceptional paintings for his own collection by targeting the collection of the Rothschild Family after the annexation of Austria. Hildebrand Gurlitt supplemented them with drawings by renowned French painters. He acquired this work by Boucher from a Parisian art merchant in 1942.

Cornelius Gurlitt hoarded the sculpture along with many other artworks for decades in his Munich apartment. Before his death in 2014, he consented to have his stocks researched and — should they include articles of stolen art — have them returned to their rightful owners in accordance with the Washington Principles on Nazi-looted art.

In September 2010, customs officials stop an elderly man in a train from Zurich to Munich. His name: Cornelius Gurlitt. He is carrying a suspiciously large amount of money with him. Even though that's not forbidden, border guards report him to tax officials. In 2011, a search in his Munich apartment leads to an astonishing discovery.

Among junk and expired cans of food littering the residence, the investigators discover thousands of art works which had gone missing during World War II. Behind this invaluable art collection are countless episodes of deep pain and injustice.

The art works are presumed to have been looted by Nazis, which confiscated so-called "degenerate art" and stole works from Jewish collectors. Paintings by Pablo Picasso, Henri Matisse, Marc Chagall, Paul Klee, Max Liebermann (pictured: "Two Riders on the Beach"), as well as other modern classic paintings, make up the collection. The name Gurlitt was already notorious in Germany's art world.

Hildebrand Gurlitt, Cornelius Gurlitt's father, was an art dealer during the Nazi era. He traded "degenerate art" for the planned Führer Museum in Linz and sold paintings which had been confiscated from Jewish owners or museums abroad. After the war, he reported that his private collection and all business records had disappeared in the Dresden fire bombing of 1945.

In 2011, his son Cornelius Gurlitt sells Max Beckmann's painting, "The Lion Tamer." A 1931 label of the Flechtheim Gallery glued on the back of the painting should have made the art world suspicious. This Jewish art dealer had fled Germany in 1933, leaving many art works behind. The painting was auctioned for 864,000 euros (about $1 million).

In November 2013, the seized art collection in Munich is made public. Since 2011, the art historian Meike Hoffmann (pictured) has been in charge of determining where the paintings come from and finding their owners. It's an extremely complicated task, charged with moral, legal and historical questions.

Provenance researchers like Meike Hoffmann search for the origin and history of a painting. Labels on the back of the art works or business records from art dealers and auction houses can provide clues. Cornelius Gurlitt inherited the paintings from his father, yet descendants from Jewish families claim to be the legitimate owners and want them back.

According to German law, the Gurlitt case is clear: The owners' right to reclaim Nazi-looted art expired after 30 years. The Bavarian Ministry of Justice proposed to change the law surrounding this time limitation in cases where people knowingly possessed looted art. The draft is still being examined.

The German and Bavarian governments have promised to clear up all aspects of the Gurlitt case, setting up a special task force. Until now, little has happened - only two paintings have been identified as Nazi-looted art. The experts led by Ingeborg Berggreen-Merkel are still searching for the origins of the paintings. Some of the alleged heirs are elderly and may not live to see the result.

David Toren, 89, is suing Germany and Bavaria. He wants the painting "Two Riders on the Beach" back. It had once belonged to his great-uncle David Friedmann, who was killed by the Nazis in 1942. Descendants of Jewish collectors whose art was confiscated are growing impatient.

New headlines shake the art world. Cornelius Gurlitt's lawyers uncover a series of paintings by Monet, Manet, Corot, Courbet and Renoir in a seemingly abandoned house belonging to the Gurlitt family in Austria. The art works are claimed to be part a private collection. Could these also be Nazi-looted art?

Months later, Cornelius Gurlitt strikes a deal with the German government. He is ready to allow all paintings suspected of being Nazi-looted art to be subjected to provenance research. In exchange, he gets back the works seized in 2012. On May 6, Cornelius Gurlitt dies at the age of 81 in Munich. But the thriller goes on.

Surprisingly, Cornelius Gurlitt bequeaths his collection to the Museum of Fine Arts Bern. He mentions in his will good memories of time spent in Switzerland. The German government greets this last will, but a part of the Gurlitt family feels bypassed.

Two of Gurlitt's cousins, who were not mentioned in his will, commissioned a psychiatric report to determine whether he was in his right mind when writing the legal document. The report concludes that he was not; however, the will is not contested. On November 24, the Museum of Fine Arts Bern confirms that it would accept Gurlitt's collection.