Dutch systems specialist Paul Post had glimpsed the notebooks that contained his father’s Nazi-era diaries before, but when he rediscovered them in an attic 15 years ago, the recent retiree finally had time to closely examine them.

Post, 74, had no idea that they would ultimately lead to Argentina, where in September the daughter of a high-ranking Nazi official was charged with concealing an 18th-century painting looted during the Holocaust.

In his diaries, Post’s father described working in the Netherlands’ diamond bureau when it was taken over by the Nazis. As Post began researching the events, one name jumped out: the Nazi official Friedrich Kadgien.

Kadgien oversaw the Nazi looting of diamonds and gold from occupied countries. Post began to follow Kadgien’s wanderings after the war, hoping to solve the mystery of the diamonds that historians say are still missing. He learned by chance that Kadgien was believed to have also possessed looted art.

The hunt led him and Dutch journalists to the peaceful residential neighborhood home of Patricia Kadgien, 60, in the seaside town of Mar del Plata in Buenos Aires province, where “Portrait of a Lady” had been hanging prominently in her living room. The reporters spotted it in a real estate listing in August.

Her attorney, Carlos Murias, told Reuters that she did not know about claims the painting had been looted from the collection of Jewish art dealer Jacques Goudstikker and she has denied having hidden it.

Nazi-related discoveries like this occasionally pop up in Argentina, which after the war received both Holocaust survivors and dozens of Nazi war criminals, including Adolf Eichmann and Josef Mengele. In February, President Javier Milei met with representatives of the Simon Wiesenthal Center, who asked for help accessing materials to investigate Nazi banking activities in Argentina. And last May, the Supreme Court announced it had found thousands of Nazi labor organization membership booklets in its basement archive.

Post’s unlikely role in the painting’s discovery underscores the complexities of finding Nazi-looted art today. An estimated 600,000 pieces were stolen from Jewish families, and more than 100,000 have never been returned.

“I’m just an amateur, I’m not a historian, nothing at all,” said Post. “I knew I was right on Kadgien.”

A FATHER’S WAR DIARIES RESURFACE

In 2010, Post’s family was cleaning out his mother’s house in Driehuis, a town just outside of Amsterdam. In the attic, they found three diaries written by his father, who died in 1976 at age 60.

In the diaries, Wim Post recounted how in 1942 the Nazis ordered the country’s diamond traders to turn over their precious stones, confiscating about 71,000 carats at the Amsterdam Diamond Exchange.

Paul Post, then recently retired from Hewlett-Packard, began visiting the Netherlands’ national archives to research the diamond confiscation. There he came across Kadgien’s name.

Shortly before Germany’s surrender in May 1945, Kadgien fled to Switzerland, where officials received a tip that he had carried out large transfers of diamonds, according to Regula Bochsler, a historian in Zurich. But in 1950, Kadgien received a visa to travel to Brazil, ultimately making his way to Buenos Aires.

Post reached out to the Dutch newspaper Algemeen Dagblad to share his father’s account of the diamond raid, and in 2015, investigative reporter Cyril Rosman published a piece about the diaries. Post later published “The Diamond Heist,” a book on the subject.

In 2020, Post noticed that the Cultural Heritage Agency of the Netherlands listed Kadgien online as possibly having possessed “Portrait of a Lady” by the Italian artist Giuseppe Ghislandi — although art historians have said the painter was likely his contemporary Giacomo Ceruti — as well as an Abraham Mignon still life. He met with the agency’s researcher Perry Schrier, and told him he had tracked Kadgien’s family to Mar del Plata. But Schrier, who confirmed he had met with Post, couldn’t help him.

“I said, ‘I think I know the location, where it could be, and that is in Argentina,’” recalled Post. “But he said, ‘Yeah, ok, it could be possible, but how can we know that it is on the wall in their homes?’”

In June 2024, Post contacted Yael Weitz, an attorney for Goudstikker’s family. In an email exchange seen by Reuters, he offered to provide leads on the two missing paintings if she could provide him with information on Kadgien. She ultimately said that her team didn’t have anything to share.

Post then turned to journalists again. Last April, he reached out to Rosman with more information on Kadgien’s post-war travels. They had tried to contact Kadgien’s daughters in Argentina through the years and Rosman asked Peter Schouten, a freelance journalist in Buenos Aires, to try again.

“We were not looking for the paintings in particular,” said Rosman. “At that time we were mostly thinking about the diamonds that were looted, so we wanted to know what happened to that.”

When Schouten rang the bell at Patricia Kadgien’s home in August, there was no answer. But he saw a for-sale sign in her yard. The reporters checked the real-estate listing and spotted the painting in one of the photos of the property. They could barely believe their luck.

“I thought, ok, is it really this simple, a picture that’s missing for 80 years is here above a couch in the living room?” said Rosman.

The day after they published a story on the painting’s discovery, police raided the home. But in the painting’s place was a tapestry of horses. Eight days later, Kadgien’s attorney handed the painting over to authorities.

Federal prosecutors have charged Patricia Kadgien, who runs a small clothing business, and her husband, Juan Carlos Cortegoso, a go-kart mechanic, with aggravated concealment and are investigating more than 20 drawings and prints, as well as two portraits, also seized from their home and from the home of Patricia’s sister in Mar del Plata.

“The attitude was to hide the painting,” the case’s prosecutor, Carlos Martinez, told Reuters. “We think that isn’t indicative of someone that doesn’t know what they have.”

COMPETING CLAIMS TO THE PAINTING

Goudstikker’s family have fought for decades to get his paintings back.

The art collector died when he fell into the hold of a boat as he was fleeing the advancing Nazis with his family in May 1940. But in a small black book, he had listed “Portrait of a Lady” along with more than 1,000 pieces in his collection.

In what historians describe as a forced sale after his death, top Nazi official Hermann Goering purchased about 800 of Goudstikker’s paintings. Weitz, the attorney who represents Goudstikker’s family, said that Goering’s associate, Alois Miedl, sold “Portrait of a Lady” to Kadgien in 1944.

The family has recovered 300 to 350 works of art, including 200 that had been mostly hanging in museums that the Netherlands agreed to return in 2006.

Charlene von Saher, Goudstikker’s granddaughter who lives in Greenwich, Connecticut, said her family informed the Kadgiens of their claim to “Portrait of a Lady” after the journalists published their story. Paolo Plebani, curator at the Accademia Carrara in Bergamo, said it is worth upwards of $100,000, but attorneys for the Goudstikker family said it is impossible to determine the value before examining the condition and confirming the artist’s identity.

“I just hope that they would be people who would feel like doing the right thing and correcting a historical injustice,” von Saher told Reuters, saying that the discovery was “like a movie.”

But Patricia Kadgien hasn’t relented. She has filed a claim in civil court that says her father’s sister-in-law bought the painting from the Wallraf-Richartz Museum in Cologne in 1943. It said the painting was “legitimately possessed” by her father and that she inherited it after he died. The museum told Reuters the painting was never part of its collection.

The claim said that she removed the painting from her home “for security reasons,” thinking she was the victim of “a virtual scam” when she started receiving calls from a journalist in August.

As for Post, he still wants to know what happened to the diamonds that were tied to Kadgien. Martinez, the prosecutor, said authorities did not find jewels of value or from the war-period in the Mar del Plata home.

Saskia Coenen Snyder, a Dutch professor of modern Jewish history at the University of South Carolina, said it is very hard to prove that Nazis took diamonds with them to South America. “I’ll give him credit for at least spending years of his time pursuing, uncovering stories and truths that not everybody wants to do or has been able to,” she said of Post. “He’s a bit of a pit bull.”