A small convoy of military trucks rumbled to a stop at the site of the ancient Banteay Chhmar temple in northern Cambodia. The armed men inside—members of a rogue military unit—set up roadblocks around the vine-shrouded shrine, cutting it off from the outside world. Then the soldiers put local villagers to work with jackhammers, stripping Banteay Chhmar of its 800-year-old treasures.

The temple's finely sculpted enclosure wall portrayed the rise of the wealthy Khmer Empire that once spanned much of mainland Southeast Asia. The wall's detailed scenes of battles and royal processions were a crucial source of data for archaeologists and historians. But in two weeks of dogged labor, the looters hacked apart a 98-foot-long section of the sculpted wall, chopped it into blocks, and loaded it onto six large trucks. Then they disappeared with the plunder.

The looting of Banteay Chhmar in 1998 remains the most infamous antiquities theft in Cambodian history. Only a small portion of the wall has been recovered. Exactly who planned this operation and many other temple lootings, and how the stolen artworks were trafficked, are questions that have long perplexed archaeologists.

But in a study published today in the British Journal of Criminology, criminologist Simon Mackenzie and lawyer Tess Davis, both of the University of Glasgow in Scotland, expose what they describe as the inner workings of the transnational criminal network that organized the looting of Banteay Chhmar and several other major Cambodian sites.

"I don't think I can overstate how important this study is," says archaeologist Morag Kersel of DePaul University in Chicago, an expert on looting and artifact trafficking in Jordan and Israel. Until now, archaeologists have had little hard data "on how artifacts go from the ground to the consumer, but this study has it in a nutshell, and I see a lot of the same patterns and networks in the area I work in."

The Banteay Chhmar temple was famous for its wall carvings. Looters hacked one wall into pieces.

View Images The Banteay Chhmar temple was famous for its wall carvings. Looters hacked one wall into pieces. PHOTOGRAPH BY KRIS LEBOUTILLIER, NATIONAL GEOGRAPHIC CREATIVE

Not a "Victimless Crime"

The Cambodian study is part of a groundswell of new research on the shadowy world of antiquities trafficking. Although reliable statistics on the illicit trade are scarce, a recent survey of 14,500 field archaeologists indicated that looters are at work in at least 103 countries worldwide.

Most countries have laws prohibiting the plundering of sites and the export of their stolen cultural heritage, but wealthy collectors and other buyers continue to purchase looted artifacts, often viewing the trade as "a victimless crime," Mackenzie says.

But several studies, both ongoing and published, link antiquities traffickers to a range of serious crimes, including corruption, money laundering, prostitution, and the smuggling of drugs and endangered wildlife. Moreover, new evidence from Afghanistan and Iraq suggests that artifact smuggling networks are closely connected with violent insurgents.

As a result, researchers are urging government officials and law enforcement agencies to crack down harder on the trafficking networks. Like blood diamonds, researchers say, blood antiquities may well be helping to finance terrorism in the Middle East and elsewhere.

And far beyond war zones, tomb robbers and traffickers are destroying vital data on ancient civilizations and contributing to criminal enterprises. "In a very real sense," writes archaeologist Neil Brodie of the University of Glasgow, "looted archaeological sites are crime scenes."

This 10th-century Cambodian statue of a temple wrestler was displayed at the Norton Simon Museum in California.

View Images This 10th-century Cambodian statue of a temple wrestler was displayed at the Norton Simon Museum in California. PHOTOGRAPH BY JAE C. WONG, ASSOCIATED PRESS

From the Killing Fields to Wealthy Collectors

In an old gray stone building tucked away on the University of Glasgow campus, researchers at the Scottish Centre for Crime and Justice Research are gathering data on this underground trade from around the world. For a multimillion-dollar project dubbed Trafficking Culture, team members are analyzing how traffickers smuggle and launder looted artifacts, and how they can be stopped.

"Our project is unique," says team member Donna Yates, an archaeologist focusing on the antiquities trade in South and Central America. "We are the first academic group to have criminologists, lawyers, and archaeologists all working together."

From the outset, Mackenzie and Davis saw Cambodia as a country of particular concern. It possesses a rich archaeological legacy and has a modern history of warfare. In 1970, Khmer Rouge insurgents rose up against the Cambodian government, eventually seizing power and instituting genocidal policies that claimed the lives of 1.7 million people.

During the almost three decades of war and chaos that followed, looters ransacked dozens of ancient Cambodian sites. In 2010, the International Council of Museums (ICOM) published a Red List of Cambodian Antiquities at Risk, alerting international law enforcement agencies, customs officials, and others to rare objects targeted by smugglers, from silver figurines and bronze drums to sandstone statues of Hindu gods.

In the summer of 2013 Mackenzie and Davis flew to the Cambodian capital, Phnom Penh, to study the antiquities traffickers. There they opted for a novel approach. Rather than interviewing antiquity shop owners in hopes of gleaning leads, they decided to start at the bottom of the networks—with the looters themselves.

Dancers perform at a ceremony to welcome three looted statues back to Cambodia on June 3, 2014.

View Images Dancers perform at a ceremony to welcome three looted statues back to Cambodia on June 3, 2014. PHOTOGRAPH BY SOVANNARA/XINHUA/CORBIS

How Looters Do Business

With researcher Thanaren Than of Cambodian Heritage Trust, Mackenzie and Davis traveled to Banteay Chhmar and five other heavily looted temple complexes in Cambodia. Each of these ancient sites was surrounded by small villages, and the team started by interviewing local elders. With the elders' assistance, the researchers tracked down local people who took part in the looting or witnessed it firsthand.

To their surprise, the looters expressed regret for their actions and volunteered information about the ringleaders. "Cambodian people believe in karma," says Than, "and the looters knew they did a bad thing. They wanted to do the right thing for their future life."

The local informants identified a former member of the Khmer Rouge as the man next up the trafficking ladder. He agreed to talk to Mackenzie and Davis. When the two researchers arrived with books on Cambodian antiquities, he told them about several sandstone statues that he and his workers had taken from local temples.

Often, he said, he sent photos of plundered statues to those farther up in the network to arrange a price. On occasion, however, he sent photos of objects in situ, offering to loot them. A high-quality statue could bring $1,250 (in today's U.S. dollars). In a particularly memorable and profitable 12-month period shortly before the Khmer Rouge forces finally surrendered, this man and his associates sold 92 looted statues.

The stolen antiquities went to the next link in the chain—the heads of an organized crime ring in Sisophon, a small Cambodian city near the Thai border. Widely feared in the community, these individuals controlled a range of criminal enterprises, from drug smuggling to prostitution, and one had reportedly personally organized the two-week-long looting of Banteay Chhmar. With expertise in smuggling, these crime bosses arranged the transport of stolen antiquities across remote stretches of the Thai border, and dealt ruthlessly with any competition.

In Thailand, a receiver accepted the stolen goods and conveyed them to a dealer in Bangkok, the apex of the trafficking network. This dealer, says Mackenzie, was "a Janus figure." Like the ancient Roman god, he had two very different faces, one that gazed down into the criminal underworld of traffickers, another that looked up into the world of wealthy collectors and buyers. He concealed the black-market origins of artifacts, effectively laundering them to attract a legitimate, well-heeled clientele.

"At the Janus point in the network, you are entering the international market," Mackenzie says. "Before that it was all underground, but the Janus figure is the portal into the legitimate market." Once laundered, a museum-quality statue can fetch hundreds of thousands of dollars from an international buyer.

The new findings, says Davis, show in detail how looted antiquities go from the ground to the consumer. And what is surprising, she adds, is the small number of links between violent criminals in Cambodia and wealthy buyers around the world. "There are very, very few steps between a looted Cambodian temple and a collector."

Sites like Ur in Iraq (above) are vulnerable to looting and neglect during times of conflict.

View Images Sites like Ur in Iraq (above) are vulnerable to looting and neglect during times of conflict. PHOTOGRAPH BY UNDERWOOD AND UNDERWOOD

Looted Treasures Financing Terrorism

But profits from the illicit antiquities trade are not only flowing into organized crime. For more than a decade, insurgencies have fostered wide-scale looting of ancient sites in the Middle East. In 2003, ICOM published an Emergency Red List of Iraqi Antiquities at Risk. Three years later, it followed up with another one for Afghanistan.

Today many observers wonder if insurgents in Afghanistan and Iraq are raking in profits from this black market in order to purchase weapons and finance terrorism.

Detailed information is hard to come by, says Neil Brodie, a Trafficking Culture team member who has been studying the issue for nearly a decade. Tracing trafficking networks on the ground in Afghanistan or Iraq, as Mackenzie and Davis did in Cambodia, is currently too dangerous, but reports from the U.S. military and other sources point to a connection between insurgents and the antiquities trade.

From 1996 to 1998, for example, the Society for the Preservation of Afghanistan's Cultural Heritage reported, based on eyewitness accounts, that militant Islamist fighters were looting ancient Afghan sites, sometimes with bulldozers, to obtain marketable antiquities.

In 1999, Mohamed Atta, the al Qaeda member who hijacked and flew an American Airlines plane into the North Tower of the World Trade Center in New York, tried to sell Afghan antiquities to a German university professor. Atta, according to information released by the German intelligence agency, claimed that he was selling artifacts in order to purchase an airplane.

More recently, an American expert on Afghan trafficking networks has uncovered a direct link between Afghan insurgents and the antiquities trade. In a report published by the Combating Terrorism Center at West Point, Gretchen Peters, a senior fellow on transnational crime at George Mason University in Fairfax, Virginia, describes how a terrorist organization known as the Haqqani Network—which is allied with al Qaeda—collects protection money from traffickers moving looted artifacts into Pakistan.

In an interview conducted by Peters's research assistant, a Haqqani commander described receiving a $3,000 payment from a trader, and noted that many "businessmen who smuggle precious stone, sculptures, and other historic artifacts ... pay dues to the Taliban to avoid trouble on the road." These funds can then be used to purchase weapons.

Violent factions in Iraq also appear to be cashing in on the illicit antiquities trade. In 2007, Colonel Matthew Bogdanos of the U.S. Marine Corps Reserves, head of the investigation into the 2003 looting of the Iraq Museum in Baghdad, reported that insurgents turned to artifact smuggling to generate funds after the world banking community froze assets belonging to their supporters.

Bogdanos cited a report describing the contents of several underground bunkers in Iraq where U.S. Marines captured five heavily armed insurgents in June 2005. The chambers, he reported, contained night-vision goggles and automatic weapons, as well as "30 vases, cylinder seals, and statuettes that had been stolen from the Iraq Museum."

Other classified U.S. Army documents suggest that antiquities smugglers often conducted business with insurgents during the Iraq War. In a paper published in the International Journal of Cultural Property last year, Peter Campbell, a Ph.D. student at the University of Southampton in England, summarized several classified documents posted online by WikiLeaks. In a report from December 2005, for example, U.S. forces received intelligence that insurgents were planning an attack with rocket launchers on targets in and near Nasiriyah, a city close to the ancient Sumerian ruins of Ur. The leaked army document noted that the man who sold the rocket launchers to the insurgents and concealed the weapons until needed was an antiquities smuggler.

Taken together, says Brodie, the evidence links terrorists in the Middle East to the black market in looted artifacts. In archaeologically rich areas, he says, it's hard to imagine that any armed groups would ignore the opportunity to profit from the underground trade.

More than 150 items, including these statuettes, stolen from the Iraq Museum during the U.S. intervention in 2003 were returned to Baghdad on May 21, 2014.

View Images More than 150 items, including these statuettes, stolen from the Iraq Museum during the U.S. intervention in 2003 were returned to Baghdad on May 21, 2014. PHOTOGRAPH BY AHMAD AL-RUBAYE/AFP/GETTY IMAGES

Reaching a Tipping Point

Shutting down this global black market will not be easy, particularly in countries where war and civil strife prevails. But many archaeologists think it's time to redouble the efforts.

In regions such as western Turkey, for example, looters have ransacked 90 percent of all known Iron Age burial mounds in search of jewelry and other artifacts, while in northern Pakistan, thieves have pillaged or destroyed 50 percent or more of the ancient Buddhist shrines and monasteries in search of artifacts.

View Images SATELLITE IMAGE COURTESY OF SARAH PARCAK

In this 2009 satellite image of el Hibeh, Egypt, few looting holes are seen.

View Images SATELLITE IMAGE COURTESY OF SARAH PARCAK

This 2012 image of the same area shows many more looting holes.

If decisive action is not taken soon, remaining sites in key regions could be destroyed in a generation. "In Egypt," says archaeologist Sarah Parcak of the University of Alabama at Birmingham, "we are literally seeing sites disappear before our eyes."

To help halt the destruction, Parcak and her colleagues are working on new ways of tracking and monitoring looting. In Egypt, she explains, concentrations of looting holes can be seen from space, and her team is using high-resolution satellite images taken over time to look at changes in looting patterns.

Satellite archaeology: revealing loss, unveiling the unknown

Sarah Parcak and her team are not only using satellite imagery to monitor looting from up in space. They're also collecting images to identify buried landscapes with astonishing precision, thus contributing to archaeological finds. In 2011, relying on infrared satellite pictures, Parcak and her team identified 17 potential buried pyramids, some 3,000 settlements, and 1,000 tombs across Egypt.

View Images GRAPHICS: 5W INFOGRAPHICS. SOURCES: SARAH PARCAK AND GREGORY MUMFORD, UNIVERSITY OF ALABAMA AT BIRMINGHAM; DIGITALGLOBE

"What the imagery allows us to do is identify what parts of the sites have been affected over time and why," says Parcak, whose work is funded in part by the National Geographic Society. "In looking at sites across the Middle East, we can see that some sites have been very badly affected post-revolution and some pre-revolution."

For example, Parcak and her colleagues examined satellite images taken before and after the 2011 Egyptian Revolution of two major sites in Egypt, el Lisht and el Hibeh. The team measured the extent of looting holes in each image and compared the results. In a case study published online by DigitalGlobe, Parcak "found a 400 to 500% increase since the events of 2011."

But the archaeologist thinks that such knowledge is power. Armed with statistical data on the spread of the looting, archaeologists can make their cases for increased protection of sites more forcefully than before. "I think we are at this really interesting tipping point," she says, "where we can map, monitor, and protect both known and unknown sites, and we have to decide what we are going to do with that technology."

View Images SATELLITE IMAGE COURTESY OF SARAH PARCAK

Few looting holes are visible in this 2010 satellite image of el Lisht, Egypt.

View Images SATELLITE IMAGE COURTESY OF SARAH PARCAK

In 2013, the same area is pockmarked with holes.

Others say that cracking down on looting is only part of the answer. Neil Brodie thinks governments and law enforcement agencies need to go after the kingpins of the trafficking networks more often. "I would like to see fewer customs seizures that result in just sending the objects back, and more enforcement agencies going after the crooks," says Brodie. "And I'd like to see full police investigations of the networks, knocking the principal players down."