Though it may have been Nazi war loot stolen from a Jewish gallery owner, a Cézanne masterwork currently on tour at the Dayton Art Institute is legally part of the Rau Collection.

The oil painting The Sea At L’estaque (1876) had been seized by a French court in 2000 while on display with other works from the Rau Collection at the Musée du Luxembourg in Paris until the painting’s true ownership could be determined.

The story goes back to 1940 when France fell to the Nazis. At the time, the painting was the property of Josse Bernheim-Jeune, owner of Gallery Bernheim-Jeune in Paris.

The prestigious gallery had built Cézanne’s reputation, championing his work during the artist’s lifetime.

With the Nazi occupation of Paris, the SS carried out “Aryanization” or transfer of ownership of Jewish businesses to non-Jews.

It was at this time, according to Michel Dauberville —Bernheim-Jeune’s grandson and current co-owner of the gallery — that his grandfather was forced out of his business and fled to Lyons, which was not yet occupied by the Nazis.

“He had his safe opened by the person who took over the gallery for the Nazis,” Dauberville told The Observer in a phone interview from Paris.

“The person wasn’t allowed to open the safe, but he did. We had no witness, except two or three papers.”

According to Dauberville, the painting was documented as stolen in a catalog published after World War II by American, French and Russian armed forces, called The Register of Looted Works of Art.

“It was in the book of works stolen during the war,” he said.

Dauberville said five other paintings were stolen from his grandfather’s safe.

Thirty-two more paintings were stolen from his family during the war, he said, including Renoirs and Van Goghs.

Josse Bernheim-Jeune ultimately died of natural causes in Lyons in 1941.

Dauberville said he and his parents escaped to Switzerland in 1943. The family reopened the gallery in 1952.

In 2000, Dauberville was informed by the Art Loss Register — an international registry of stolen art works — that the Cézanne in the Rau Collection might be the one stolen from his grandfather.

Dauberville said he was not aware that his parents had attempted to regain the Cézanne through the French courts in 1949. The court system rejected that claim.

“We didn’t know it had already been decided in 1949, he said. “At that period we still had judges against us (the Jews). If it had been judged in the last five years, it would have been different.”

Because it had already issued a decision 53 years earlier, the French justice system dismissed the case in 2002.

“It’s finished. There’s no way to respond,” Dauberville said. “We would have to find something new and it could take 10 to 15 years. The cost had been large. We decided to live with it. We signed a paper with them (Rau’s estate) saying we would stop everything.”

Dayton Art Institute Director Alex Nyerges said that he saw these most recent court papers.

“They were sent as part of the negotiations for the exhibit,” he said.

Nyerges said that he had no doubts about exhibiting the Cézanne, saying its history is not “cloudy.”

“If this were a collection that was unknown I would probably pause a bit,” he said.

“Dr. Rau had a great dislike and hatred for the Nazis. I understand he was particular.”

A German pediatrician, Dr. Gustav Rau built his life’s work caring for children in Africa. He died in 2002 at the age of 79.

Rau bought the Cézanne in 1981 at Sotheby’s.

“Is the record complete on the Cézanne? As far as we can tell,” Nyerges said.

The Rau Collection exhibit, at the Dayton Art Institute until Feb. 28, features rarely seen European masterpieces from the 15th to the 20th centuries.

Rau willed his art collection to UNICEF of Germany. According to the terms of his will, the entire collection of more than 800 works  — including the Cézanne — must be sold in 2026 to raise funds for Third World charities.