"The Adoration of the Christ Child" in Rome's Galleria Borghese has long been attributed to Fra Bartolomeo, but not with confidence.
Now chief restorer Elizabeth Zatti, nearing the end of a year-long restoration of the painting, says she has discovered a fingerprint previously unseen.
That, along with stylistic similarities, has scholars thinking that the painting may be by Leonardo da Vinci.
The picture, three feet in diameter, is famous for its round shape, and is known as "Il Tondo."
It includes precious materials such as as lapis lazuli and gold.
Photos of the painting, which was created in the late 15th or early 16th century, will be flown to Kracow, Poland, to compare the newly-discovered fingerprint with one on da Vinci's "Lady With an Ermine".
The restoration uncovered symbolism associated with da Vinci, such as wild primrose, which represents resurrection, and blue veronica flowers, symbolizing the eyes of the Virgin Mary.
In addition, the Virgin Mary has the large, masculine hands seen on many da Vinci women.