Infrared scans revealed the image of a well-dressed gentleman under "The Blue Room," painted during the artist's early days in Paris. Art experts are eager to learn who the man was, how he was connected to Picasso, and why his portrait was painted over.
"We will try to identify, if at all possible, who the sitter might be," said Susan Behrends Frank, associate curator for research at The Phillips Collection in Washington D.C.
"We're trying to gather information about individuals Picasso had any opportunity to have contact with, or whose paths he may have crossed during his crucial early weeks in Paris," she said.
Researchers are hoping that material from the Museu Picasso in Barcelona, and another museum in Paris, will offer clues to solving the puzzle.
Knowing more about the man shown seated with his right hand touching his cheek could help researchers understand the process and changing style of the celebrated artist who died in France in 1973 at age 91.
A conservator at The Phillips Collection, a private institution, suspected something was underneath the "The Blue Room" as early as the 1950s when he noticed inconsistencies in the brush strokes. In 1997, X-ray images revealing a murky image confirmed his suspicions.
But it wasn't until infra-red scans were performed in 2008 that a clearer portrait of the bearded man in a bow-tie was revealed.
Earlier this year, art experts from The Phillips Collection, The National Gallery of Art in Washington, Cornell University and the Winterthur Museum in Delaware, all of whom collaborated on the research, discussed their findings. They determined, judging by the brush strokes and pigment, that both paintings had been done in haste by Picasso in 1901.
"We can see where it fits in with his works in an important transition time for him," said Frank, adding that the style of the painting suggests the summer of 1901 in Paris.
"One of the things we will try to do is understand more about the timeline between these two paintings," she added.
The portrait of the mystery man is not the first found under a Picasso painting. It was not uncommon for struggling artists to re-use a canvas.
Frank said that discovering other aspects of Picasso's early career adds to the larger understanding of the moment he was becoming the artist he is known as today.
"It's like being a detective trying to decipher these enticing morsels of information to try to knit them together into a more comprehensive picture," Frank added.
"The Blue Room," which has been part of The Phillips Collection since 1927, will be displayed in South Korea from next month until early next year. It will also be the focus of an exhibition at The Phillips Collection planned for 2017.