SELLS — Elena Toribio Lazaro and 10 others slipped across the border into Arizona at about 3 a.m. on a warm night in June.
Twelve hours later, as the sun beat down on the Baboquivari Valley and the temperature climbed to 105 degrees or more, the 24-year-old mother became sick and struggled to walk. A 28-year-old man she knew from their hometown of Acambay in central Mexico carried her for a while.
Then he set her down under a tree and placed a shirt over her for shade. Their guide and the rest of the group left the pair behind. When she stopped breathing, her companion went looking for help.
By the time U.S. Border Patrol agents made it to that tree that afternoon, she was dead.
Toribio died in a smuggling corridor that has claimed the lives of 229 border crossers since the beginning of fiscal 2000 — more than three times the average number of deaths in other segments of the Border Patrol's Tucson Sector, the Arizona Daily Star found in an analysis of 1,156 deaths recorded by the Border Patrol. Most died of the heat.
"It is the deadliest migrant trail in the United States," said Mike Wilson, a tribal member who sets up and maintains water stations on the Tohono O'odham Reservation.
The corridor is an 18-mile-wide swath of mesquite and cactus running from Mexico north through Sells, bordered on the east by the craggy Baboquivari Mountains and on the west by open desert. Agents know it as the "Little Tucson corridor," named for Ali Chukson, the O'odham village near where smugglers often pick up people who have trekked through the desert.
This route has been a deadly, double-edged sword for illegal border crossers in the last decade. Remote, sparsely populated, with a relatively small presence of Border Patrol agents and near foothills and canyons that offer cover, it has been an ideal route for avoiding detection. But those same characteristics mean people who get lost, sick or dehydrated face long odds of surviving.
"If you are out here in the middle of nowhere, it's all or nothing," said Sgt. Vincent Garcia of the Tohono O'odham Police Department. "You don't know where you are at, you are from another country, you don't know what the terrain is like, you don't know where the roads are at. ... You just need to keep heading north."
There are four main reasons for the density of bodies found in the deadly corridor, said representatives from the Border Patrol, the Tohono O'odham Nation and immigrant-rights groups that track deaths.
● More people, more problems.
The area is one of the busiest human- and drug-smuggling routes along the Southwest border. The Casa Grande station, which covers the area, has registered the third-most apprehensions within the Tucson Sector each of the past three years.
The sector, which stretches along 262 miles of border from the New Mexico line to the eastern edge of Yuma County, has been the busiest along the Southwest border since 1998. In fiscal 2007, the sector accounted for 44 percent of all apprehensions on the U.S.-Mexican border, averaging more than 1,050 a day.
With such heavy foot traffic, the probability that some of the migrants are going to get sick or dehydrated increases.
● Remoteness is a double-edged sword.
Unlike other areas of the border, where entrants can give up and walk to a nearby highway, ranch or house, or find an agent for help, there are few houses and fewer agents to provide help along the 25-mile trek north from the San Miguel Gate to the Sells area.
Bill Milne, a member of Borstar, the Border Patrol's, Search, Trauma and Rescue team, said the desert doesn't care if you're young or old, a man or woman or in good or bad physical condition.
"It's like the devil; it will take what it can get. It's indiscriminate," he said.
● The Baboquivari Mountains offer both solace and pain.
Many groups hike north along the foothills of the Baboquivaris because the trails offer more cover from helicopters and agents, some shade and lower temperatures. But walking up and down the hills can make the journey even more taxing.
A few people — mostly drug smugglers — hike high into the mountains, where paths are at 5,000 feet or even higher. The GPS coordinates show few bodies in the mountains, but officials believe there are likely many more that haven't been found yet.
In July, when O'odham police responded to the Alambre Fire, which burned 7,500 acres near Kitt Peak, they happened across four bodies, Garcia said.
"They are there. It's just that nobody is going in there to go look around," Garcia said.
● The end of a long, hot, dry journey.
By the time people get within a few miles of Arizona 86, they've often been walking three to five days, are low on food and water and probably have been beaten down by the elements.
In the summer, temperatures are usually two to five degrees higher in the desert corridor than in Tucson, said Tom Evans, a National Weather Service meteorologist.
At the end of this demanding journey, two things happen, officials say: People start making poor decisions, such as shedding clothes or drinking dirty cattle water; or they reach a point where they feel they've made it, let up and their body relaxes, often resulting in death. This often happens when entrants reach a home or spot where they're told they'll be picked up or get help, Garcia said.
"It's almost like they say, 'Oh good, you found me, I'm saved, I can relax,' " Garcia said. "And when they relax is when they die. As long as they keep trying to fight for survival, they are all right."
On Toribio's final day, there had been no rain for 47 days. By the time the young woman reached the tree where she died, near Fresnal Canyon Road about 17 miles north of the border, she was likely low on water.
She was just two miles west of the village of Topawa off the reservation's main highway, Federal Route 19. That's where her friend, Omar Celedonio López, walked for help.
People often die just short of the villages, Garcia said. Authorities found four bodies in the past year near a baseball field just outside Sells. On the day before Thanksgiving, they found the body of a man a mere three-fourths of a mile from Baboquivari High School in Sells. The body had been there about a year.
Older generations of O'odham, some of whom entered the country illegally, treated border crossers with respect and consideration, offering water, shade and medical attention to those in need. But in a gradual change since about the 1970s, today's O'odham are less trusting of illegal border crossers and also fear that by helping them they may incriminate themselves in the people-smuggling business.
"Once the people were very much more open, but now doors are shut," said Margarita Gonzalez, whose O'odham grandfather crossed from Sonora many years ago.
Those neighborly practices have vanished due to the sheer number of people coming through the desert, said Wilson, the tribal member who sets up water stations.
"Even if we wanted to accommodate that massive exodus, we don't have the resources," he said.
Wilson cites another factor in the deaths: The Indian nation doesn't allow Tucson-based Humane Borders, which maintains 87 water tanks across the rest of the Arizona border, to put up stations on the reservation.
Wilson, with the help of fellow tribal member David Garcia, maintains six of his own water stations. He has four, each with two 55-gallon water barrels, along Fresnal Canyon Road and two on Arizona 86 east of Sells. As a Tohono O'odham member, he is allowed to put out the water. He believes the lack of water is the single most significant factor in the deaths.
"If they had access to potable water in strategic areas, they wouldn't be dying," Wilson said.
Humane Borders formally requested permission to install water tanks, but was denied because the tribe doesn't want to attract illegal entrants, said the Rev. Robin Hoover, the founder of the Tucson-based group. That decision continues to frustrate the organization, he said.
"If I could put out enough water to fill up one swimming pool in that area, we could take as many as 25 percent of the deaths out of the Tucson Sector," Hoover said.
Tribal officials say they do their best to rescue entrants and shut down smuggling operations but emphasize they are dealing with a problem created by the federal government.
They had fewer crossers and hardly any deaths until federal enforcement efforts shifted traffic their way.
For the past several years, the Tohono O'odham police have been collecting about 65 bodies a year, Sgt. Garcia said. This year through Nov. 27, the Indian nation found the bodies of 72 illegal border crossers, and eight more have died in automobile crashes, Garcia said. The 46 autopsies performed so far on those bodies have cost the tribe $80,020, he said.
Signs point to shifting traffic patterns for smugglers and their groups, which might lessen the tribe's burden, if it hasn't already.
The increased presence of Border Patrol agents, the building of two SBInet camera towers and the construction of vehicle barriers around the San Miguel Gate at the international line have been forcing smugglers to shift their routes east to the Altar Valley and farther west on the reservation, officials and locals say.
Shifting away from the Baboquivari Valley might mean fewer deaths, but don't expect them to cease altogether.
These two corridors have been deadly, too, according to the death data from the Border Patrol from 2000 to 2007: The 172 bodies found in the Altar Valley is nearly 2 1/2 times the average in other segments. The 131 bodies in the corridor that stretches from Sells west into the Gu Oidak and Tecolote Valleys are nearly twice the average.
DID YOU KNOW ...
Increased enforcement under operations Gatekeeper in San Diego and Hold the Line in El Paso forced smugglers to shift their routes to Arizona in the mid-1990s. They showed up first in the Nogales area, but by 1998, responding to a beefed-up Border Patrol presence, they shifted to Naco and Douglas. By 2000, the smugglers had begun moving west to the Baboquivari Valley, which continues to be an important smuggling crossing.