VIENNA.- On Wednesday, an auction house in Europe will put a painting by Gustav Klimt up for sale, with a preauction estimate of at least 30 million euros (about $32 million).

Whoever buys it will obtain a painting by an artist whose major works rarely come up for sale, but also a portrait whose subject, provenance and current ownership are either unknown, not public or the subject of debate.

The auctioneer selling the painting is not an international heavyweight such as Sotheby’s or Christie’s, but im Kinsky, a local house in Vienna whose biggest sale until now was in 2010: $6.1 million, for a painting by Egon Schiele.

At a news conference in January announcing the sale of the mysterious Klimt work, Ernst Ploil, co-CEO of im Kinsky, said: “All is in the dark. Whenever there is an argument for something, counterarguments arise again and again.”

Some of the debate centers on the identity of the young woman portrayed. Other questions have arisen about what happened to the artwork during the Anschluss, when Austria was annexed into the Third Reich.

The painting was owned by a Jewish family during that period, and there are no documents that record what happened to it during those years when Austria’s Jewish population was persecuted, deported and murdered and their possessions plundered by the Nazis.

The questions surrounding the portrait have only added to the interest in the sale of this work by Klimt, one of the founders of the influential Vienna secessionist movement, whose highly decorative paintings are now among the art market’s most coveted trophies. In June at Sotheby’s in London, his “Lady With a Fan” fetched $108.4 million.

The story of this painting, known as “Portrait of Fräulein Lieser,” begins in Vienna in 1917, when a teenage daughter of a wealthy Jewish family made the first of nine visits to Klimt’s studio to pose.

Klimt’s notebook offers a clue, but an unsatisfying one, to the identity of the subject. It records each visit by a “Lis,” signifying a member of the affluent Lieser family. But Justus and Adolf Lieser, two German-born brothers who founded Austria’s first mechanical hemp rope and twine factory, each had teenage daughters.

The portrait was never finished. Art historians believe the unsigned canvas was in Klimt’s studio when the artist died in 1918, during the influenza pandemic. For decades, the painting has only been known from one black-and-white photograph that was taken in the 1920s. Afterward, the portrait’s whereabouts was largely unknown.

The auction house suggests that “Fräulein Lieser” might possibly depict one of the two teenage daughters of Henriette Lieser, who was known as Lilly: either Helene, who became a distinguished economist, or Annie, a celebrated dancer. A member of the Landau family, one of fin-de-siecle Vienna’s very wealthiest, Lilly divorced Justus Lieser in 1905 and became a patron of the Viennese avant-garde.

Im Kinsky’s suggestion is based on an inventory card on the negative of that old black-and-white photo of the painting in the Austrian National Library. The card indicates that in 1925, the portrait was hanging in Lilly’s palatial home in Argentinierstrasse.

Lilly was deported by the Nazis in 1942 and murdered at Auschwitz in 1943, according to the catalog.

But her daughters survived the Holocaust. Neither is known to have tried to find or claim the Klimt after World War II. And the painting does not appear in Lilly Lieser’s declaration of valuable assets that all Jews in Germany and Austria had to draw up for the Nazis in 1938.

However, recent research, and articles in the Austrian newspaper Der Standard, support the view that the portrait is one of Lilly’s daughters. The articles describe letters from 1961 that were recently discovered in the archive of Mumok, Vienna’s museum of modern art, that indicate the painting at that time was in the possession of a man named Adolf Hagenauer.

In one letter, Hagenauer is upbraided by a curator and future director of the museum, Werner Hofmann, who accuses him of acquiring the portrait from a Jew who had “died in the gas chambers,” as Lilly had.

During the Anschluss, Hagenauer, managing director of a family grocery business, was married to the daughter of Lilly Lieser’s butler, according to research by Georg Gaugusch, author of a 5,000-page history about the Jewish upper-middle class in Vienna.

Gaugusch and Olga Kronsteiner, who wrote the Der Standard articles, have raised the possibility that Lilly traded the painting to Hagenauer for provisions as the persecution of Jews heightened in 1938, the year in which Hagenauer is documented as applying for membership of the Nazi party.

Hagenauer ultimately gave the Klimt to his daughter, according to Der Standard. The newspaper reported that the daughter died last year, having bequeathed the painting to a distant relative, who is the undisclosed seller today. Ploil said in an email that Der Standard was correct in this detail.

But two Klimt experts, Tobias Natter and Alfred Weidinger, say the painting actually depicts a different teenage girl: Margarethe Constance Lieser, the daughter of Justus’ brother Adolf and his wife, Silvia. Adolf died in 1919. Margarethe married the Hungarian Catholic convert Henry de Gelsey in 1921 and moved to Budapest, followed by her mother in 1938.

Weidinger said in an email that in 2007 he had been introduced to Margarethe’s son William de Gelsey, an investment banker. He said de Gelsey, who died in London in 2021, with no children, had requested his help in tracking the painting.

He was convinced that Klimt had painted his mother, Weidinger said: “He said there was never any doubt about it, because his family always talked about the portrait of his mother.”

De Gelsey made a provision in his will for a donation to a Catholic charity if the painting were rediscovered and sold, but never registered the Klimt portrait as missing on the database of Art Loss Register, which locates and recovers stolen artworks.

Weidinger and Natter said they were not approached by the auction house for their opinions on the painting. Natter said in an email that “contrary to all international standards, the auction house has failed to involve the two leading Klimt experts, both of whom have published a catalog raisonne.”

Im Kinsky said in an email that it had not approached Natter because his views of the painting were known from his catalog, but it had consulted at least three independent art historians.

Im Kinsky’s auction catalog says that, as part of the effort to sell the painting, its current owners had recognized the “many ambiguities and historical gaps” in its provenance and reached “a fair and just solution” with legal successors of the Lieser family. This agreement meant that, from a “purely legal point of view,” it was “immaterial” who commissioned the painting and which of the three Lieser daughters was depicted.

Ploil said that regardless of which Lieser daughter is portrayed, the painting had been unlawfully acquired during the Nazi period. “Every form of taking away during the Nazi time has to be treated as unlawful,” he said.

Asked if de Gelsey’s nominated charity would be a beneficiary of the auction, Ploil, a partner in the Vienna law firm Ploil Boesch, said in an email that although a confidentiality clause prevented him from commenting on that specific point, “all legal successors of Adolf, Justus and Henriette Lieser are part of the agreement.”

Jil Birnbaum, a solicitor at the London law firm Wedlake Bell, which handles the de Gelsey estate, said that the heirs of William and his brother Alexander, who died in 2006, are included in the settlement.

Under Austrian law, legal agreements between owners and successors can, in certain circumstances, settle a restitution issue instead of the formal return of a looted artwork. The work then has to be granted an export license by the state. The Austrian Federal Monuments Authority issued such a license to the Klimt on Oct. 23, 2023.

“Restitution is a very delicate issue, and we have to research a lot and be very accurate about the information,” said Erika Jakubovits, executive director of the presidency of Israelitische Kultusgemeinde Wien, the Jewish Community of Vienna.

“Only the rightful heirs should be the ones to settle with,” Jakubovits said. “A legal opinion on the heirs should be prepared before starting settlement procedures,” she added, alluding to what she views as remaining questions about who are the legal heirs to “Portrait of Fräulein Lieser.”

Although the latest research reported in Der Standard takes the view that the Lieser girl is likely to be Helene, Ploil said in an email that it was important not to go too far in specifically identifying the subject of the portrait at this junction.

He noted that lawyers for the de Gelsey family “still stick to their contrary opinion that Adolf Lieser has commissioned the painting — showing Margarethe Lieser and not Helene.”

Because of the inconclusiveness, Ploil said, “the catalog will not be changed or amended.”

Natter said the identity of the girl had wider consequences. “The identity is important as it allows us to go back to the commissioner and tells us a lot about the provenance and ownership history,” he said. “It really does make a difference.”

This article originally appeared in The New York Times.