BERLIN -The late Cornelius Gurlitt, the son of a major Nazi-era art dealer, bequeathed his vast art trove to a Swiss museum, potentially complicating efforts by families to recover pieces they say were stolen from them by the Nazis.
The news comes after the octogenarian recluse, who died on Tuesday, had agreed last month to restitute all artworks that were found to have been looted. Although German jurists say that agreement should bind Mr. Gurlitt's inheritors, lawyers for Nazi-era victims and their heirs fear the development could mean further delays after months of negotiations.
The Kunstmuseum Bern said on Wednesday that it had been informed that Mr. Gurlitt had bequeathed it his entire collection. It said the news "came like a bolt from the blue, since at no time has Mr. Gurlitt had any connection with the Kunstmuseum Bern." A Munich court confirmed Mr. Gurlitt, who died at home weeks after major heart surgery, had signed a notarized testament in early 2014.
Mr. Gurlitt had hoarded his 1,400-strong art collection for decades in Munich apartments and in a house in Salzburg, Austria. Its existence was revealed in a German press report late last year almost two years after local German officials seized the Munich-based trove as part of a tax investigation.
The bulk of the artwork came from Mr. Gurlitt's father, Hildebrand Gurlitt. One of Adolf Hitler's main art dealers, he scoured occupied Europe during World War II, seizing valuable pieces for the so-called Führermuseum in Linz, Austria, which Hitler intended to make his leading art institution with Hildebrand Gurlitt at the helm.
After German authorities came under international criticism for not disclosing the Gurlitt art cache earlier, they set up a task force under the authority of the Bavarian tax prosecutors to investigate the provenance of the artworks and determine which had been looted by Nazis.
In April, shortly before Mr. Gurlitt's death, the tax authorities released the works back to Mr. Gurlitt after he agreed with Bavaria's justice ministry to restitute all work found by government-appointed experts to have been stolen. As part of the agreement, the collector had given investigators a year to determine their provenance and help arrange their restitution to families with claims on them.
A spokesman for the Bavarian justice ministry said that deal stood regardless of the newly surfaced will. The Kunstmuseum, though, declined to say how and whether it would research and restitute looted artwork until it had talked to the relevant German authorities.
The Kunstmuseum Bern is bound by international norms on art restitution known as the "Washington Principles" that Switzerland signed in 1998 along with the U.S. and Germany. These dictate that museums have a duty to research and return any art stolen during World War II to the rightful heirs.
"I'm encouraged by the fact that Swiss museums are bound by international museum codes of ethics" including the Washington Principles, said Christopher Marinello, lawyer for the family of late Parisian dealer Paul Rosenberg, which is claiming "Woman with a Fan," a 1923 portrait by Henri Matisse and one of Mr. Gurlitt's most valuable possessions.
David Toren, an 88-year-old American has claimed a 1901 Max Liebermann oil painting called "Two Riders on the Beach," is suing Germany in Washington's federal court for the return of that work.
"Germany has a legal obligation to turn over this work to us," said August Matteis, Mr. Toren's lawyer. "When a bank robber steals money from a bank, police return the money to the bank. They don't ask permission to give the money back from the robber, and his life and death is irrelevant."