The unfinished painting of Jesus and Mary has long been in the family of US Air Force Lieutenant Colonel Martin Kober, who lives in Buffalo, New York.
He and his relatives nicknamed it “The Mike” because of a family legend that it had been painted by the Renaissance artist.
The painting had hung in the Kober home but was knocked off the wall by a stray tennis ball 27 years ago, so it was wrapped it up and put behind the couch.
In 2003 Mr Kober decided to research the origins of the 25in by 19in work and eventually took it to Antonio Forcellino, an Italian art restorer and historian.
Mr Forcellino is convinced it is a genuine, painted depiction of the Pieta, Michelangelo’s famous sculpture of the body of Jesus on his mother’s lap, which is housed in St Peter’s Basilica.
In his book “The Lost Pieta,” Mr Forcellino said: “I had assumed it was going to be a copy. In reality this painting was even more beautiful than the versions hanging in Rome and Florence. The truth was this painting was much better than the ones they had.”
Mr Forcellino claims that infrared and X-ray examinations showed changes made by the artist and an unfinished area of canvas close to the Madonna’s right knee.