Few artists marked the dawn of a painting's creation as precisely and dramatically as Leonardo da Vinci did with his "Battle of Anghiari," a vast fresco of war and rage that he undertook on commission for the Florentine Republic.

"On the 6th of June, 1505, a Friday, at the stroke of the 13th hour, I began to paint in the palace," he wrote in a journal. Just then, the weather turned rotten, he reported. Bells began to toll and wind blew his paper designs all over the place. "Great rain poured down until nightfall," da Vinci continued, "and it became dark as night."

The painting's impact lived up to its thunderous conception, according to critics and commentators of the time. Such was the beauty of the fresco that it was dubbed a "school for the world," that is, a model for all artists to emulate. In 1549, a visitor to the room in Palazzo Vecchio, where the fresco covered part of a wall, called it "something miraculous."

A few years later, the room was remodeled. No one saw the painting again.

Fast forward to this summer and meet Maurizio Seracini, a biomedical engineer and art conservationist. He believes he can bring the "Battle of Anghiari" to light.

Using lasers and other electronic sensing devices, he has conducted a painstaking study of the Room of the Grand Council, where "Battle" was located. The results, he said, suggest that da Vinci's fresco still exists. When the room was altered in 1563, a separate wall was built in front of the painting and, Seracini maintains, a cavity exists between the new wall and the old. Look behind the newer wall, he says, and you will see the fresco.

"There would have been no reason to destroy the 'Battle of Anghiari' in order to remodel the room," he said in an interview. "That kind of thing wasn't done, and especially it would not have been done with this fresco." He made his findings public at a news conference in June.

The claim made headlines in Italy -- the possibility that an unseen da Vinci exists had the mesmerizing attraction of uncovering an unknown poem of Dante's or a hidden statue by Michelangelo. While finding an intact "Battle" is still a long shot, a controversy quickly arose that has all the fury of the June 6, 1505, storm: Who should be tasked with revealing the fresco and possibly reaping the fame and financial benefits?

Seracini's contract with the city of Florence to study the council room expired in 2002. City officials have declined to grant him more time. "Just as we were getting close, suddenly the city saw the possibilities and it is thinking about money," the engineer said. Documentaries, rights to print reproductions and fees from investigators to do further studies are all part of the potential booty, he said.

City officials say Seracini is after a cornucopia of benefits for himself. Simone Siliani, Florence's culture adviser, said officials were upset that Seracini held the news conference in June and recruited donors to continue his research without telling them. "Our duty is not to make movies or scoops," Siliani said. "Our duty is to study and let the people know about the history of the city."

In the meantime, the search for the "Battle of Anghiari" has come to a halt. City officials say they're unconvinced and plan no follow-up.

The painting was commissioned at one of the sparkling heights of Florence's cultural and political history. A republican government, 13 years old at the time and beset by enemies in Italy and abroad, wanted da Vinci to glorify a 15th-century battle in which the Florentines bested an army from Milan.

When da Vinci put brush to wall that day in 1505, he was using experimental oil-based pigments and a kind of plaster that allowed him to paint on a hard surface.

That much is reliably known, but from there the mystery builds. Did da Vinci complete the giant scene, a tangle of horses and men in agony and aggression? Did his newfangled plaster hold or melt, as some historians say? Da Vinci had run into technical problems before. He had painted "The Last Supper" in tempera and it faded badly within 20 years.

Complete or unfinished, faded or bright, the fresco deeply impressed many people who saw it in subsequent years. In 1549, a Venetian man named Agnolo Doni wrote a letter to a friend advising that, after entering the palace, passing a statue of David by the sculptor Donatello and climbing a large staircase into the Big Room, he should "diligently take a look at a group of horses and men (a piece of the battle of Lionardo da Vinci) that will appear as something miraculous."

But by 1563, the republic was upended, and the demands of artistic glorification changed. The Medici rulers, dismissed from Florence in 1492, had returned, and they wanted some scenes in the council room depicting battles their armies had won. They commissioned Giorgio Vasari, the famous artist, architect and biographer, to remodel the chamber, raise the ceiling and paint new, giant murals depicting the Battle of Marciano. (1554, Florence beats Siena.)

Vasari had commented on many art objects and their creators, including da Vinci and the "Battle of Anghiari." Once, he praised the fresco as "most excellent and masterful for its marvelous treatment of figures in flight." But in surviving documents, he mentioned nothing of what he did with it as he set about renovating the room.

If the "Battle" were still there, Vasari would not have destroyed it, Seracini insists. In his view, the Battle of Marciano work is painted on the new wall, not over da Vinci's fresco. "Vasari had to redo the room. That was the order. To do so, he had to thicken the wall to support the new ceiling. But that does not mean destroying da Vinci's fresco. He would have just left it intact just behind his wall," Seracini said.

There is a final possible clue in the mystery, Seracini surmises. On a banner among the ranks of Vasari's painted soldiers the words cerca trova are inscribed. That means "search and find." They are the only words on the four monumental Vasari paintings in the room. Is it code for finding the "Battle of Anghiari"?

"I think we know where the painting is," said Rab Hatfield, a Syracuse University art historian who argues that historical eyewitness accounts corroborate Seracini's findings.

Seracini's search for the battle fresco began as a project to map the original room, which for centuries has been the seat of Florentine government. His Editech company makes diagnoses of the "anatomy" of artworks, he said. He tries to discern the real from the fake, the original from restorations, the state of old and deteriorating works and how to fix them.

For the council room project, Seracini used lasers, radar and thermographic survey machines, which can read density or material and hidden spaces, to map every nook and cranny of the room. He found sealed-up windows behind plaster and walls, traces of the original roof, entrances long blocked up and the route of the staircase mentioned by Doni.

Seracini says he has virtually pinpointed the location of the "Battle of Anghiari" on the east wall. He wants to scan the area with a machine that can read pigments hidden behind Vasari's mural. If there is color there, he wants to run a tiny fiber optic cable to scan the old wall, now in the interior. That would require drilling a little hole in Vasari's painting.

"We can't destroy one painting to find a few chips of old paint behind," Siliani cautioned.

Seracini said the hole would be tiny and made so that the surface of the Vasari mural could be replaced or restored. "It's not as if other paintings haven't had pieces restored," he said.

And if there is no "Battle of Anghiari"? "Even that would be a contribution to art history. We would know it is lost," he said.

Maurizio Seracini says a painting by Leonardo da Vinci lies hidden on a wall behind a giant mural by Giorgio Vasari portraying the Battle of Marciano. Vasari's painting is shown behind him on a wall of Florence's Palazzo Vecchio.