NANTERRE — He's got Palmyra on his mind. Sitting as his desk in the judicial police office in Nanterre, near Paris, Ludovic Ehrhart is staring at his holiday pictures: four black-and-white snapshots of the ancient Syrian city. He put them up last summer, just after ISIS started to destroy it. He's been to Palmyra twice, 20 years ago.

"At daybreak, in this huge place, you're alone," he recalls. "A Bedouin passes by with a camel. The atmosphere is surreal. You're beyond the boundaries of time."

He never thought that the Mesopotamian oasis would one day find its way into his case files. A 45-year-old colonel in the gendarmerie, Ehrhart has been leading a very special branch since 2014 — the Central Office for the Fight Against Cultural Goods Trafficking (OCBC), which hunts down criminals who steal works of art. With his 25-strong unit (including 15 investigators), Ehrhart now finds himself at the heart of a global struggle against antiquities trafficking, a source of revenue for terrorists.

"I like to work with art objects that sometimes have an age-old history," he says. "It's very appealing." You won't find a gun on his desk, but there is a copy of the weekly La Gazette Drouot, which covers art auctions. "There's a treasure hunt side to this job," he says.

His techniques are similar to those used by other branches of the judicial police, with a network of informers to look after, wiretapping, sometimes infiltrations. But his cases take longer to crack.

Knowledgeable in art

His assistant director, 54-year-old commandant Corinne Chartrelle, has filled her office with paintings and art books. An admirer of painter Suzanne Valadon and of the Flemmish school, she's been working here for 11 years. In her spare time, she likes to try her hand at painting and sculpting. "If I was in the drug squad, I'd cry my eyes out," she says.

Another colleague, 51-year-old Jean-Luc Boyer, clad in leather and denim, heads the archive department. He is the office's institutional memory, having been here for 22 years. As a young police officer in Paris, he found out about the OCBC when the headmaster of an art school came to him to file a complaint. "I found my vocation that day," he says. Like Chartrelle, "Lulu" taught himself art history in the evenings and couldn't see himself working anywhere else.

When an investigation is successful in Nanterre, it always ends in a secret location: the chest. That's where the police officers keep the seized works. Ehrhart takes us to the small, windowless spot. "Whatever you do, don't describe that object there on the right," the colonel instructs. "That would compromise our investigation. Also don't talk about that one on the left. We haven't arrested the thieves yet."

A relief in the Temple of Bel before it was destroyed — Photo: Jerzy Strzelecki

We cast a timorous glance. There are fabulous paintings, a luxurious piece of furniture, an Egyptian antiquity, five golden chalices, a faux bronze. All the latest trends in art trafficking are represented here.

"Painting theft is pretty much outdated," the chief explains. "With exchange of information between countries, traffickers know they'll have a hard time reselling master paintings. So they specialize in archeology instead, in ransacking churches and in counterfeiting." As for the crooks, there's no typical profile. "We deal in everything," Jean-Luc Boyer says. "From lowlifes from the banlieues to organized crime guys, not to mention wealthy antique dealers."

From the Mideast to Europe

For months now, the OCBC has been tracking Syrian and Iraqi antiquities on the Paris market, and is ready to launch an investigation at the slightest suspicious discovery. Heritage looting has accelerated since ISIS took the Iraq city of Mosul in June 2014. The police go over art galleries with a fine comb, and from auction room to auction room, follow them on the Internet.

"They sometimes come in pairs without warning and examine our transaction books," says Daniel Lebeurrier, whose Gilgamesh archeology gallery in Paris was searched last year. "It's always a bit scary."

There have been no miraculous finds yet. "There are a few small objects and old coins on sites like eBay or Le Bon Coin," Ehrhart says. "But we haven't found anything major." Yet statues, manuscripts and other valuable works are crossing borders. ISIS-linked traffickers are targeting countries that are fond of Middle Eastern art: the United States, Britain, Germany, Switzerland and France.

"These age-old networks take three, five, sometimes even 10 years before selling the works on the official market," the colonel says. Enough time to launder what's now known as "blood antiquities." They give them a new place of origin, often in free ports, where there are no customs regulations, like in Dubai or Zurich. This trafficking, like that of oil, drugs, weapons or indeed people, raises cash for ISIS. Experts believe it brings in between $30 and $100 million every year.

To fight against this sprawling market, these "art cops" have limited means. "Sure, OCBC officers enjoy a great legitimacy, but how do you want them to deal with all their cases with just 25 people?" says Olivier Lange, director of Hôtel Drouot, among the most important auction houses in Paris. By comparison, Italy's Carabinieri art squad has a staff of 250.

Cooperation with foreign investigators

Part of the OCBC's strength lies in its connections with foreign police forces — the Italians, the Belgians or the FBI. Faced with "global trafficking of cultural property of $3 to $6 billion a year," according to UNESCO expert Edouard Planche, investigators stick together.

On the day we visit, Ehrhart receives a guest from Cairo. Gen. Ahmed Abdelzaher, clad in white shirt and grey suit, is chief of Egypt's antiquities police. In his country, trafficking of cultural property is booming. At the very beginning of the revolution that ousted President Mubarak in January 2011, some 50 objects were stolen from Cairo's museum, among them a wooden figure of Tutankhamun and a statue of Nefertiti. Plundering hasn't stopped since. "Since the Egyptians know a few traffickers' networks, we share our working methods," says Ehrhart, who visited Cairo a few months ago.

Contrary to Egypt, trafficking is actually slowing in France. That's why OCBC agents have also been dealing with investigations of art forgery since 2009. That now represents about one-third of their cases. Finding counterfeits is a lot of work, but it helps with decorating the office. There is a fake Soutine in one office, a fake Modigliani in another, both recently seized, and they are used as examples to train interns and magistrates.

French police inspect seized property — Photo: DGPN-SICOP

The forger was a piece of work. In 2013, an art connoisseur alerted the OCBC after noticing several imitations of famous painters being auctioned on the Internet at a very low starting price. The seller explained in the item descriptions that he'd found what he believed to be paintings belonging to his grandmother in his attic. The paintings looked like famous works of art, though with variations.

"Without saying it, the seller was suggesting that this could be a previously unknown work from a famous painter," explains Olivier, one of the unit's investigators. Amateurs and collectors alike were tempted to try their luck for 500 to 4,000 euros (20,000 for the most expensive one), thinking they would have a chance to become super rich.

At least 80 victims fell prey. In June 2013, the police arrested the forger with his wife in southern France. A search of his workshop proved that the paintings hadn't been found in his attic. "He was a smart ass who was good at painting and engaged in mass forgery," Olivier says. "He painted on old daubs after coating them." The police seized 300 imitations of Manet, Renoir, Van Dongen and more from his workshop and from purchasers for a total value of 700,000 euros ($760,000).

Targeting forgeries

The man claimed he hadn't lied or forced customers to buy his objects. The pair were brought before the judge, placed under investigation and released. The police concluded the investigation in mid-2015, but there's been no ruling yet. "We've tried to understand the story the forger built to convince his victims," Ehrhart explains while buying a coffee from the vending machine. "It's all based on suggestion. Intellectually speaking, it's interesting. Actually, for an investigator, a crook is always interesting."

The OCBC also dealt with the Le Guennec affair, in which an electrician and his wife were accused of fencing 271 Picasso paintings. The pair were handed a two-year suspended sentence in March 2015, but they appealed the decision. Anne-Sophie Nardon, who represented the painter's daughter-in-law in the case, praises the OCBC for their work. "Even with just 25 people, they're indispensable. They know the market well and are very competent," she says.

Each of them dreams of discovering the unfindable painting. "My grail would be to return one or two Rembrandts, or even the missing Vermeer to Boston," says Jean-Luc Boyer.

Boston was the heist of the century. In 1990, two people masquerading as police stole 13 works of art worth an estimated $500 million from the Gardner Museum. "The OCBC has worked on the case twice, before folding for lack of results," explains Corinne Chartrelle.

"Among the legendary works, there's also Corot's Le Chemin de Sèvres, stolen from the Louvre in 1998," Ehrhart says. "If we found it, I'm not saying we'd be the kings of the world, but…"

Perhaps it would be a bit like seeing Palmyra whole again.