Journalists from the Dutch newspaper Algemeen Dagblad found the painting while browsing an online real estate listing, where it was seen hanging above a green sofa in a living room. The listing has since been removed.

The house belonged to one of the daughters of Friedrich Kadgien, a high-ranking Nazi official who stole the painting.

The artwork, which belonged to Jacques Goudstikker, a well-known Dutch Jewish art dealer, had long been listed on international and Dutch registers of missing works.

On Tuesday, local prosecutors entered the house in Mar del Plata while Patricia Kadgien, one of Kadgien's daughters, was present. However, the painting was not there, according to Carlos Martínez, the federal prosecutor leading the investigation.

Prosecutors seized some folders from the house, as well as prints believed to date back to the 1940s. There may be other stolen objects in the house, Martínez said.

Goudstikker kept a small black notebook in which he cataloged his inventory of some 1,400 works of art. He took it with him when he fled the Nazi-occupied Netherlands in 1940 with his wife and son on a cargo ship bound for England.

Goudstikker died in an accident aboard the ship. But his widow kept the notebook, which has since served as key evidence in a legal battle to recover the artworks stolen from his family.

The Nazis looted Goudstikker's artworks through the forced sale of his gallery to Hermann Göring, one of the most powerful members of the Nazi party, and his banker, Alois Miedl.

After World War II, Kadgien, Göring's financial advisor, left Germany and moved to Switzerland. From there, in a journey shrouded in mystery, he managed to leave Europe and settle in Argentina.

"The big question we ask ourselves," said Cyril Rosman, one of the journalists who found the painting, "is what the daughters know about this painting. Do they know its history? Why would they give the painting such a prominent place if they know it was looted?"

Rosman said he had been investigating Kadgien's past when his colleague in Argentina learned about the real estate listing.

It was not immediately possible to contact Kadgien's daughters.

Rosman's discovery this week excited art experts, historians, and Goudstikker's heirs. Yael Weitz, the heirs' lawyer, said on Wednesday that she had filed a legal claim on behalf of the family to recover the painting.

Before the real estate website photo, the painting had not been seen in color images, only in an old black-and-white photograph.

"The first thing I thought was that there must be many works like this all over the world," said Charlène von Saher, Goudstikker's granddaughter, in an interview on Tuesday. "These works have already survived hundreds of years and could survive hundreds more without being returned to their rightful owners."

Before appearing on the real estate website, the painting had only been seen in an old black-and-white photo.

"In the 20 years we've been doing this work, we've never experienced anything like this, a painting appearing in this way," said Perry Schrier, an investigator at the Dutch Cultural Heritage Agency, a government organization.

After the discovery, Annelies Kool, another researcher at the agency, said she felt inspired to continue searching online to see if photos published by the sisters revealed any other missing artworks, and she discovered that they did.

Through a Facebook search of some "family snapshots," Kool said she found what she believes is another 17th-century painting that had been missing since World War II: a still life by painter Abraham Mignon that had also been stolen by Kadgien. (However, that painting did not belong to Goudstikker.)

It is likely that both artworks have remained in the family since the end of World War II, Kool said.