Could there be an unknown Leonardo da Vinci painting at the Philadelphia Museum of Art?

François Mühlberger has an obsessive passion for Renaissance painting. A Belgian administrator for a Spain-based olive oil company, he pores over centuries-old artworks in his free time. It was light fun until he became convinced that he had made a major discovery in 2022: a Leonardo da Vinci painting wrongly attributed to a different painter at the Philadelphia Museum of Art.

The amateur art historian was reading a book about the painter Fra Bartolomeo when he first saw Bartolomeo’s Adam and Eve with Cain and Abel (1512). The painting was acquired by PMA in 1933 as part of the John G. Johnson collection (the same collection that held a different painting now thought to be a true Vermeer). Eve, partially draped in a light blue fabric, holds a baby in one arm and the hand of a toddler with the other hand. Across from her sits the outlined profile of Adam, naked and holding a farm hoe. Behind them are mountains, trees, and billowing clouds with a mysterious figure in red, holding up his arms in the distance. Mühlberger was struck by the unfinished work, and couldn’t shake the feeling that it was painted by Leonardo, not Bartolomeo.

There is a Leonardo in Philadelphia, Mühlberger writes in his book, The Leonardo of Philadelphia, which was published in French last year, then translated into English in 2024. In less than 60 pages, he argues that because the work was unfinished (common for Leonardo), has visible fingerprints on the canvas (Leonardo blended colors with his hands), shows the tip of Adam’s penis (Mühlberger says the prudish monk Bartolomeo would never), and contains a subliminal nod to Cain killing Abel, it must be the genius of Leonardo. His conviction is clear, but the evidence is muddled.

The implications of this claim are not lost on Mühlberger. If proven true, the discovery would rattle the art world in Philadelphia and beyond. The only other Leonardo held in a U.S. museum is his Ginevra de’ Benci at the National Gallery of Art in Washington, and there are very few known works — an estimated 15 to 20 paintings — by the Italian master that have been authenticated.

Attribution debates are not new, and often these investigations take years of study from experts and scholars. In 2017, Leonardo’s Salvator Mundi became the most expensive artwork ever sold, fetching $450 million, but a year later, one scholar argued that the painting was almost entirely done by one of the painter’s studio assistants. The attribution is still supported by most Leonardo scholars, but it’s an ongoing conversation.

In this case, however, Mühlberger’s claim lacks the legitimacy of academic experience. With a 1999 degree in art history from Belgium’s University of Liège, he accepts that he is no expert, but believes that Adam and Eve with Cain and Abel deserves a serious investigation nonetheless — and he is incredibly persistent.

Mühlberger first contacted the PMA in November 2022 to request additional photographs of the painting so he could study the piece and publish them in his book. The museum obliged, sending 10 photos including X-ray and infrared images. A friend in Belgium, Bernard Quickels, believed the Leonardo argument and published the book under a new publishing company. Ahead of publication, Mühlberger and Quickels sent copies to PMA head Sasha Suda and awaited her reply. The museum said its experts would review it.

Months went by. Mühlberger sent several emails, with increasing urgency but which went unanswered, inquiring about the status of the investigation:

“I know that it may seem surprising, even unbelievable. But I am not a novice, and I am convinced I am right. I think I know the painted work of Leonardo like no one else,” he wrote in November 2023. “You will have to face the facts and assume that this little painting is definitely not by a monk painter, but of the hand of Leonardo da Vinci. You only need some courage for it. The same courage I took to write such an essay, knowing in advance the cold reception that the academic world would reserve for it.”

After he requested additional photos of the painting’s wooden panel earlier this year — he believes that analyzing the age of the wood could confirm a more accurate creation date — the museum said it would need to examine it further before sending more images, and that the panel is so thin that it would not be possible for such an analysis.

“We take these claims as seriously as we can with the resources we can,” a PMA spokesperson said recently. “We’re certainly not ignoring it, but they take time to look into. We’ve simply not done the research.”

Mühlberger has sent the book to roughly a dozen experts and has heard back from four. “They are not in accord with me,” he said. “It’s a Leonardo, I am sure. I did my job and I think that time will give me wisdom. Time will do the rest.”

Renowned Leonardo expert Martin Kemp, a professor emeritus of art history at Oxford University who has also taught at Princeton, was one who replied. While Kemp could see affinities with Leonardo, he believed the painting could be attributed to Fra Bartolomeo or another contemporary, Mariotto Albertinelli. (The painting was initially attributed to Albertinelli, but in 1906, experts agreed on Bartolomeo.)

His research is a good try but not credible, Kemp said.

Undeterred, Mühlberger continues to wait on the museum. “I don’t want to change the world. I only want to change the attribution of a single painting,” he said. He and Quickels plan to put The Leonardo of Philadelphia in local bookstores soon, hoping greater attention will quicken the process.

Mühlberger is also working on another book about the misattribution of a painting at the Met, but he’s not ready to go public just yet.