Could a lost fresco by Leonardo da Vinci have remained hidden behind another wall painting in Florence for more than 450 years? It’s a tantalizing idea, and one that Maurizio Seracini has been pursuing since the 1970s. Last December, after receiving permission from Florentine authorities, Seracini and his team drilled six holes in the wall painting that may conceal da Vinci’s “Battle of Anghiari.” But critics are saying that there are even more holes in the theory and the science behind it.

The story begins in 1505, when Leonardo started work on “The Battle of Anghiari” in the Hall of the 500 in Florence’s Palazzo Vecchio. Giorgio Vasari, an admirer of da Vinci who is often considered the first art historian, wrote in his “Lives of the Artists” that Leonardo completed only one section of the fresco and abandoned it when his experimental technique of applying oil paint directly to the wall proved to be a failure. In 1563, Cosimo I de’ Medici had Vasari renovate the hall and paint six new frescos.

Seracini, an engineering professor at the University of California at San Diego, first suspected that Vasari may have preserved the lost Leonardo behind his own fresco when he noticed a flag in Vasari’s painting that reads “cerca trova” — “seek and you will find.” The Center of Interdisciplinary Science for Art, Architecture, and Archaeology at U.C. San Diego, the Kalpa Group, and the National Geographic Society funded his research, and it was determined that there was an air gap between the Vasari and a brick wall behind it.

However, Massimiliano Pieraccini, an engineer who conducted radar tests with Seracini and other scientists and was the lead author of a 2005 article on the testing, told ARTINFO France via email that in his opinion “there is not enough scientific evidence for carrying out destructive analysis.” According to Pieraccini, the gap occupies the entire eastern wall, and there is no suggestion that a protective niche was built to house the fresco. However, the 2005 article did conclude that it was possible that there could be a cavity able to preserve “some fragments of the lost fresco.”

Seracini and his team asked to drill 14 holes into the Vasari painting to insert endoscopic probes and search behind it. The Opificio delle Pietre Dure, a conservation authority that is part of Italy’s Ministry for Cultural Heritage, granted permission to drill six. According to a National Geographic press release, locations were chosen that were cracked or previously restored, so that there would be no damage to Vasari’s original work.

Still, the drilling encountered major opposition. Cecilia Frosinini, head of the wall paintings department at the Opificio delle Pietre Dure, stepped down from her leadership position in protest. Tomaso Montanari, an art history professor at the University of Naples, circulated a petition against it that ultimately gathered 530 signatures, including those of Keith Christiansen, Jayne Wrightsman curator of European painting at the Met, and Dominique Thiébaut, head curator of the Louvre's paintings department.

Those opposed to Seracini’s search are concerned that so far he has not shared his findings with the scientific community so that they can be independently verified. According to a March 12 National Geographic press release, analysis of red, beige, and black pigment samples retrieved by the probes suggests that they are traces of paint, and the black material in particular shows “a chemical composition similar to black pigment found in brown glazes on Leonardo’s ‘Mona Lisa’ and ‘John the Baptist.’”

But just how convincing are these results? The testing was performed by two private Italian laboratories: Editech and Pontlab. Editech just happens to be owned and operated by Maurizio Seracini. Montanari told ARTINFO France via email that “the amount of pigments involved is extremely small, and no proper database exists for anyone to verify that a color ... was used exclusively by Leonardo.” For the analysis to be convincing, Montanari says, it should be performed in a double-blind test by two respected laboratories and published in a peer-reviewed journal. In a phone interview, Cecilia Frosinini told ARTINFO France that the chemical compounds that were found could be pigments or some other substances on brick or stone, and she objects that "Seracini is always speaking about his own interpretations, not about the raw data." And eminent Leonardo scholar Martin Kemp suggests on his blog, "let's wait until something really definite is found, and let's get the technical material in the public domain at the same time as the press stories." On Monday, the Florence paper La Repubblica reported that the Opificio delle Pietre Dure will conduct its own analysis of the pigment samples, and Massimiliano Pieraccini told ARTINFO France that this was “a step in the right direction.”

If the science here is not so rigorous, Montanari thinks that the National Geographic Society bears some of the blame. It is a “commercially-minded institution,” Montanari says. “One of the real problems with this case —perhaps the biggest — is that it involves an operation of marketing, not of scientific research.”

“Finding the Lost Da Vinci,” which aired on the National Geographic Channel on March 18, certainly looked like an infomercial for the project. The program’s narrator describes opposition to the drilling as a “media feeding frenzy” and an “attack from the press,” but none of the experts opposed to it is interviewed or even mentioned by name. Instead, scientists in lab coats decry the opposition to their work and are then seen boring holes into the painting while dramatic music plays. A National Geographic spokesperson told ARTINFO France via email that the producers did speak to “other individuals with differing opinions,” but that “I don’t believe the ones contacted were willing to be interviewed on camera.” It’s worth pointing out that, while the National Geographic Society is a non-profit institution, the National Geographic Channel is a joint venture of National Geographic Television and Film and Fox Cable Networks.

There is a general consensus that Vasari made a more significant contribution as an art historian than as a painter. Yet drilling holes into a 450-year-old fresco is a pretty radical step, especially when non-invasive approaches could still be explored, such as further radar exploration with improved technologies, as Pieraccini suggested in an email to ARTINFO France, or a gamma-ray imaging camera, which an unsuccessful Kickstarter campaign tried to raise funds for last fall. (Seracini did not respond to an email request to comment on the merits of these non-invasive alternatives.)

So what fate awaits the Vasari fresco? A National Geographic spokesperson told ARTINFO France that the next steps “will be determined by officials in Italy,” and Florence Mayor Matteo Renzi, who has been a supporter of the project, did not return an email request for comment. But the Kalpa Group’s Web site states that Seracini “hopes that it will be feasible for Florentine authorities to bring in experts to remove the exterior fresco by Vasari, extract the Leonardo painting, and then replace the Vasari fresco.” If Seracini really thinks that a Renaissance fresco can be taken down and then restored to its previous condition, he can look forward to having a lot more controversy on his hands.