Everett Fahy, former head of European paintings at the Metropolitan Museum of Art, says a painting long-attributed to the workshop of Francesco Granacci is actually by Michelangelo.

Stylistic elements and a look at the underpainting with infrared led Fahy to the conclusion that "Saint John the Baptist Bearing Witness" was misidentified.

The Met bought the painting at Sotheby's London as by the "close circle of Francesco Granacci" for £60,000 decades ago. As Granacci, the work may be worth £400,000 today, but if re-attributed to Michelangelo, the value might exceed £150m (about $232 million).