TOHONO O’ODHAM NATION, Ariz. — A fresh footprint in the dirt, fibers in the mesquite. Harold Thompson reads the signs like a map.
They point to drug smugglers, 10 or 11, crossing from Mexico. The deep impressions and spacing are a giveaway to the heavy loads on their backs. With no insect tracks or paw prints of nocturnal creatures marking the steps, Mr. Thompson determines the smugglers probably crossed a few hours ago.
“These guys are not far ahead; we’ll get them,” said Mr. Thompson, 50, a strapping Navajo who follows the trail like a bloodhound.
At a time when all manner of high technology is arriving to help beef up security at the Mexican border — infrared cameras, sensors, unmanned drones — there is a growing appreciation among the federal authorities for the American Indian art of tracking, honed over generations by ancestors hunting animals.
Mr. Thompson belongs to the Shadow Wolves, a federal law enforcement unit of Indian officers that has operated since the early 1970s on this vast Indian nation straddling the Mexican border.
Tracking skills are in such demand that the Departments of State and Defense have arranged for the Shadow Wolves to train border guards in other countries, including some central to the fight against terrorism. Several officers are going to train border police in Tajikistan and Uzbekistan, which border Afghanistan, and in several other countries.
In the renewed push to secure the border with Mexico, the curbing of narcotics trafficking often gets less public attention than the capturing of illegal immigrants.
But the 15-member Shadow Wolves unit, part of Immigration and Customs Enforcement, is recruiting members to reach the congressionally authorized complement of 21. And the immigration agency is considering forming a sister unit to patrol part of the Canadian border at the Blackfeet reservation in Montana, where concern about drug trafficking is growing.
“Detecting is one thing, and apprehending is something entirely different,” said Rodney Irby, a special agent in Tucson for the immigration agency who helps supervise the Shadow Wolves. “I applaud the technology; it will only make the border more secure. But there are still going to be groups of people who penetrate the most modern technology, and we need a cadre of agents and officers to apprehend them.”
The Shadow Wolves have seized nearly 30,000 pounds of illegal drugs since October, putting them on pace to meet or exceed previous annual seizure amounts. They routinely seize some 100,000 pounds of illegal drugs a year, Mr. Irby said.
They home in on drug smugglers, who use less-traveled cattle tracks, old wagon-wheel trails and barely formed footpaths to ferry their loads to roads and highways about 40 miles from the border.
The Tohono land, which is the size of Connecticut and the third-largest reservation in area in the country, has long vexed law enforcement. Scores of people die crossing here every year in the searing, dry heat of summer or the frigid cold of winter. And its 76-mile-long border with Mexico, marked in most places with a three- or four-strand barbed-wire fence that is easy to breach, is a major transshipment point for marijuana, Mexico’s largest illicit crop.
Adding to the challenge is that drug smugglers have enlisted tribal members or forced them into cooperation, sometimes stashing their loads in the ramshackle houses dotting the landscape or paying the young to act as guides. Several tribal members live on the Mexican side, and those on the American side have long freely crossed the border, which they usually do through a few informal entry points that drug traffickers, too, have picked up on.
How much the Shadow Wolves disrupt the criminal organizations is debated. Officials said they believed the group’s work at least complicated drug smuggling operations — the Shadow Wolves have received death threats over the years — but they said they could not estimate the amount of drugs making it through.
Marvin Eleando, a Tohono who retired from the unit in 2004, said he believed the Shadow Wolves got just a small fraction of the drugs moving through the Tohono lands. Mr. Eleando estimated it would take about 100 Shadow Wolves to truly foil the smugglers, who employ spotters on mountaintops who watch for officers and then shift routes accordingly.
Still, he said, the unit must keep up the effort because the drugs, and the gun violence often associated with trafficking, imperil tribal members.
“The kids get mixed up in this and then don’t want to work anymore,” Mr. Eleando said.
Lately, according to the Border Patrol and Immigration and Customs Enforcement, drug seizures in Arizona, and especially around the reservation and the Tucson area, have surged, and the size of the loads found has increased.
Officials said it was too soon to tell whether the uptick signaled a long-term pattern. But they believed it could be partly explained by the additional staffing on the border. Law enforcement officials said that there also appeared to be a bumper crop of marijuana in Mexico and that smugglers seemed to be trying to ship tons of it ahead of government crackdowns there.
“We never know how much is being pushed in our direction,” said David V. Aguilar, the chief of the Border Patrol, though he added that it seemed the amount was “higher at this point.”
Alonzo Peña, the agent in charge of Immigration and Customs Enforcement in Arizona, said investigators had many theories but little concrete information to explain the increase in trafficking.
“Is this marijuana that has been sitting in warehouses, and they are trying to get rid of it now that there is a strong hand in Mexico?” Mr. Peña said. “We just don’t know other than that we are seeing more loads and bigger loads in many areas.”
The Shadow Wolves, established with a handful of officers in 1972 as part of what was then the United States Customs Service, were the first federal law enforcement officers allowed on Tohono land.
The federal government agreed to the Tohono O’odham Nation’s demand that the officers have American Indian ancestry, a requirement still in place. Members are at least one-quarter Indian, and the current group represents seven tribes, including the Tohono.
While other law enforcement agencies, including the Border Patrol, use tracking, the Shadow Wolves believe that their experience and their Indian ancestry give them an edge, particularly here.
“I speak the language, so when we are dealing with elderly members in particular I can make them more comfortable,” said Gary Ortega, a Tohono who has been in the Shadow Wolves for nine years. “They are willing to tell us things they know or see that they may not tell another federal agent or officer.”
There is also, of course, the thrill of the hunt.
On a recent day, Mr. Thompson picked up the track around 3 a.m. and, with Mr. Ortega, stayed on it for nearly 12 hours through thorny thickets and wide-open desert. As the terrain grew craggy, Mr. Thompson kept a brisk pace, with Mr. Ortega and other officers leapfrogging ahead to help find the trail.
“Every chase is just a little different,” Mr. Ortega said, barely pausing as he followed the prints in the sand.
It grew easier as the sun rose and the smugglers kept bumping into thorny bushes and stopping to rest, leaving their food wrappers behind and coat fibers in the cat-claw brush. By midafternoon, Mr. Ortega and Mr. Thompson were tiring, too. But the scent of the men’s burlap sacks perked up Mr. Ortega, and he quickened his pace, finally catching sight of the smugglers and prompting them to bolt from their resting spot.
Left behind were 10 bales of marijuana, 630 pounds in total, a fairly typical bust, with a street value of more than $315,000.
With the weight off their backs, the smugglers showed new speed dashing to hiding places and easily outmatched their pursuers. Other Shadow Wolves drove out to pick up the load, finding their colleagues resting on the bales and grinning in satisfaction.
“When we get the dope or the guys,” Mr. Thompson said, “that’s when it ends.”
