Leonardo da Vinci's "The Battle of Anghiari" is the "LOST" of Renaissance frescos: every step towards solving its mystery seems to reveal even more loose ends. Yet a stolen copy of the long lost masterpiece was recently returned to Italy after years on the black market, possibly providing more insight into one of art history's greatest mysteries, the BBC reports.

The stolen work, a panel called the "Tavola Doria," is a 400-year old copy of Leonardo Da Vinci's fresco "The Battle of Anghiari," the Telegraph reports.

Researchers believe the "Battle of Anghiari" was painted by Leonardo in 1503, on the wall of Florence's Palazzo Vecchio. Now, this same wall is covered by the artwork of a different artist, Giorgio Vasari. Yet some art detectives are convinced Vasari painted over Leonardo's masterpiece, and the "Battle of Leonardo" remains intact and out of sight. Researcher Maurizio Seracini embarked on a controversial quest to unearth the legendary work by drilling into Vasari's fresco, but Italian authorities recently called off the costly and risky mission.

"Tavola Doria" was stolen from its owners in Naples in 1940; according to Italian police the work than headed through a Swiss art dealer, German restorators, a New York art gallery and eventually the Tokyo Fuji Art Museum.

Italian officials have been in conversation with the museum to bring the work home, since 1992, when the work was found in the Japanese capital. The two parties recently reached an arrangement giving Italy and Japan joint access to the work for 26 years, allotting the work to Italy for two years at a time and then rotating to Japan for the following four. Despite its contested authorship, experts believe in the value of Vasari's painting. “The idea that an ancient copy of a lost artwork can be as important as the original is familiar to scholars,” art historian Salvatore Settis told the BBC.

The newly returned artwork went on display this week at the Quirinale Palace, home of President Giorgio Napolitano. Next it will head to Florence's Uffizi Gallery, where it can be reunited with its sibling works in the Leonardo Room, including paintings like "Annunciation" and "Adoration of the Magi." Will the recently recovered masterpiece shed light onto the ongoing hunt for the bearded master's magnum opus? We certainly hope so, but the odds are about as good as a satisfying "LOST" finale. We can't take any more disappointments...