63 works by Egon Schiele are entangled in a legal battle over whether or not they were looted by the Nazis.

In the latest twist in a decades-long saga, a German arts restitution foundation has removed 63 works by Egon Schiele from its list of works looted by the Nazis during World War II, contradicting a ruling in U.S. court just last June, according to a report in the New York Times. The works in question had belonged to the Viennese cabaret performer Fritz Grünbaum, and while his heirs maintain that the trove of Schieles, along with hundreds of other works, were stripped from him and his wife before they were sent to concentration camps, others believe that the couple’s heirs legally sold the works in the 1950s, suggesting that they were never looted from the family.

A key point in the case is a transaction in 1956, when a Swiss dealer named Eberhard Kornfeld offered the trove of Schieles for sale without revealing their provenance. Decades later, investigators revealed that the consignor had been Mathilde Lukacs-Herzl, the sister of Grunbaum’s wife, Elisabeth Grünbaum-Herzl, who may have received the works after they were sent to Belgium, before the couple was murdered by the Nazis. If so, the German Lost Art Foundation said, the works would have been sold legally by the family, and the heirs have no right to the work.

“The fact that Fritz Grünbaum was persecuted by the Nazis is not contested [...] this does not mean that the entirety of Grünbaum’s art collection must have been lost due to Nazi persecution,” a spokeswoman for the foundation said in an email to the Times.

The family’s heirs believe the Kornfeld deal to be fraudulent, involving forged documents and withheld information, and in June, a judge in the New York State Supreme Court agreed, ruling that the work had been looted as Grünbaum’s wife had sent the work to her sister in duresses under threat of death by the Nazis. The ruling cleared the way for the heirs to sell two Schiele watercolors at Christie’s this fall, but an appeal by Richard Nagy—the art dealer who attempted to sell the works at the Salon Art + Design fair at New York’s Park Avenue Armory before having them seized at the fair by authorities—has stayed any attempt to auction the works until October 1.