If you think Mona Lisa’s smile is cryptic, you should see the mystery the Portland Museum of Art has on its hands.

No, it has nothing to do with Tom Hanks, Opus Dei or Mary Magdalene.

Instead, it’s a tale of history, international intrigue and imitation that has scholars and art lovers stumped.

“La Gioconda,” a copy of the famed Leonardo da Vinci portrait, was given to the museum in 1983 by Henry Reichold, a summer resident of Prouts Neck. It has come out of storage just in time for Friday’s release of “The Da Vinci Code.”

“It’s very hard to know what the artist was trying to tell you about her,” said museum curator Carrie Haslett.

As it turns out, it’s even harder to know who the artist was.

After the museum acquired “La Gioconda,” it was analyzed at Harvard University’s Straus Center for Conservation and Technical Studies. Pigment analyses confirmed that “La Gioconda” dates to pre-1510, whereas the original “Mona Lisa” was created between 1503 and 1507.

Though the painting’s brush strokes are consistent with those of a left-handed painter, as da Vinci was, scholars were unable to discern whether “La Gioconda” is his or the work of one of his followers.

“One of the most interesting things is, it’s not an exact copy of the ‘Mona Lisa,'” Haslett said. “Generally if you’re copying a work of art, you aim to make it look like the original. That’s a telling detail.”

The size, smile and background of “La Gioconda” differ from “Mona Lisa,” which leads some to believe the painting was an early study rather than a copy.

The work in the museum’s collection also remains unfinished, and its colors are more muted than those of the famed painting.

“It has the patina of age,” Haslett said. “You look at it and you just know it’s very, very old.”

Though the work is in less-than-perfect shape, Haslett said, it’s more instructional now than it would be if it were conserved.

“To cover it up at this point makes no sense,” she said. “We need to learn more about it.”

For the time being, “La Gioconda” will remain an unsolved mystery, which preserves some of the painting’s romance.

“It’s a little window onto a very long-lost world, kind of like the movie,” Haslett said. “It’s a piece of history – and it feels like it – from a long-lost time and place.”

“La Gioconda” will be on view through the summer months at the Portland Museum of Art. For information of hours, call 775-6148 or visit www.portlandmuseum.org.