IN ARIZONA DESERT, INDIAN TRACKERS VS. SMUGGLERS

TOHONO O'ODHAM NATION, Ariz. -- A fresh footprint in the dirt, fibers
in the mesquite. Harold Thompson reads the signs like a map.

After following fresh footprints, officers from Immigration and
Customs Enforcement loaded smugglers' marijuana last month near Sells.

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 Pena, 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. Pena 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."