A scientific investigation of two Jan van Eyck paintings, preserved in museums in Turin and Philadelphia, has cast doubt on their authorship. The paintings' theme is identical: "Saint Francis Receiving the Stigmata". One is located at the Galleria Sabauda and the other in the Philadelphia Museum of Art. Neither work is signed. Art Recognition, a Swiss company, conducted scientific experiments on the paintings using Artificial Intelligence, but they were unable to identify any of Van Eyck's signature brushstrokes. The Philadelphia painting was determined to be "91% negative", whereas the Turin picture was "86% negative". These two findings provide support to the theory proposed by some researchers that both versions are workshop paintings, meaning they were created in the artist's studio but not necessarily by him. Art Recognition's previous investigations discovered 40 fraudulent paintings for sale on eBay in 2024. In 2021, it also determined that Peter Paul Rubens's "Samson and Delilah", located in the National Gallery in London, was "91% negative", validating critics who had long doubted that the master painted it.