From Wikipedia

Athanasio Celia (also Athanasios or Athanassios Celia) is a painter, art expert and author. He is the founder of "Verticalismus". By that term he defined the theory of his art which is dominated by vertical lines. The first large one-day auction of his art was in Germany in 1995. As a “Greek artist and art expert” (Reuters) or “Paris-based painter and art historian” (The Guardian) he became worldwide known for his activities in the period 1992 - 2008.

In 1992, during an opening act of his own paintings in a gallery in Munich, he came into contact with one ancient artifact of greatest value - a golden Greek wreath (400 BC). After the examination of the object, he gave to the persons who brought him the ancient treasure information of possible interested buyers. Soon the object was sold to "the J. Paul Getty Museum" in Malibu, California. When Athanasio Celia later heard that the golden wreath had been illegally excavated, he informed the German authorities, and, years later, he handed over to the Greek state the photos which had been handed over to him by the smugglers, in order to enable the return of the object to Greece in 2007. An award-winning documentary about the subject has been broadcasted 2011 in several countries.

In a further case, in 2007, Athanasio Celia examined a notebook with sketches which had been looted by the Nazis. In his report he attributed the notebook to the Dutch painter Vincent van Gogh. His study on the notebook was published in a chapter of the book “The Notebook of Vincent” , for which Athanasio Celia also wrote the preface. One year later, in 2008, he examined again an artifact which had been looted by the Nazis. This time it was an oil painting, which he also attributed to Vincent van Gogh and according to his report “it was the last painting of Vincent van Gogh”.