00:50 Deaths Said to be Human-Smuggling Crime At least ten immigrants have died after they were found in a sweltering tractor-trailer parked at a Walmart in the summer heat in San Antonio.

At a Glance Ten people were found dead in a semi truck in the parking lot of a San Antonio Walmart.

Temperatures in the tractor-trailer exceeded 100 degrees.

Officials say the crammed tractor-trailers have been a popular method for smuggling the migrants for years.

Ten migrants died in San Antonio and dozens more were sickened in the back of a tractor-trailer that soared to dangerous temperatures and lacked water and air circulation.

When the truck departed Laredo, Mexico, to begin its 150-mile journey north to San Antonio, it didn't take long for the devastating effects of the stifling heat to set in. Some of the 90 or so passengers began to cry and plead for water as they took turns breathing through a single hole in the wall. They tried to get the driver's attention by yelling and pounding on the side of the tractor-trailer, but before long, people began to pass out.

For Thomas Homan, the acting director of U.S. Immigration and Customs Enforcement, it was an ugly reminder of a 2003 tragedy about 120 miles southeast of San Antonio, when 19 dead migrants were found inside a truck.

"It is sad that 14 years later people are still being smuggled in tractor-trailers," he said. "There still isn't water, there still isn't ventilation. These criminal organizations, they're all about making money."

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The striking similarities of the Texas tragedies demonstrate how smugglers have found a durable business model carrying large groups — often in big rigs — through an elaborate network of foot guides, safe house operators and drivers. A criminal complaint about Sunday's discovery that 10 were dead and dozens injured in the truck opens a window on their degree of sophistication and organizational muscle: passengers had color-coded tape to split into smaller groups, and six black SUVs awaited them at one transit point to bring them to their destinations.

Big rigs emerged as a popular smuggling method in the early 1990s amid a surge in U.S. border enforcement in San Diego and El Paso, Texas, which were then the busiest corridors for illegal crossings. Before that, people paid small fees to mom-and-pop operators to get them across a largely unguarded border. As crossing became exponentially more difficult after the 2001 terror strikes in the U.S., migrants were led through more dangerous terrain and paid thousands of dollars more.

Guadalupe Correa-Cabrera, a political scientist who teaches at University of Texas, Rio Grande Valley, said migrants she interviewed last year in South Texas paid $2,000 to $3,000 more to ride in the crammed tractor-trailers, considering them more effective, faster and safer than walking through the desert to a pickup point far from the border. Hundreds of border crossers perish each year in the desert, getting lost and dehydrated in extreme heat.

The growing use of trucks coincided with increased trade with Mexico under the North American Free Trade Agreement, allowing smugglers to more easily blend in with cargo, particularly on Interstate 35 from Laredo, Texas, to San Antonio, Correa-Cabrera said. Walking in the open desert more easily exposes them to U.S. Border Patrol agents.

Women, some carrying children, think they are less likely to be raped on a truck than in the open desert because there are more witnesses, Correia-Cabrera said. Riding in a big rig, she said, is "the VIP treatment."

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For smugglers, the advantage of tractor-trailers boils down to scale.

"It's like any other business: the more they move, the more profit they make," Homan said. "Rather than taking four in a car, the profit margin on tractor-trailers is a lot more."

Truck drivers are low-level cogs in a big machine, recruited in the U.S. at casinos and other places where smuggling organizations look for people who are down on their luck, desperate for quick cash and disinclined to ask questions.

James Matthew Bradley Jr., who made an initial court appearance Monday in San Antonio on smuggling charges, told authorities he was delivering what he thought was a sold vehicle from Schaller, Iowa, to Brownsville, Texas, and that he didn't know what was inside, according to the complaint. He said he was given no deadline or address to deliver the truck.

Other guides take migrants across Mexico by bus. Others join them on a raft across the Rio Grande or through the desert to a hideout or to a nearby house where they may wait days or weeks. Eventually smuggling organizations get them to major cities like Phoenix, Houston or San Antonio.

"I have to imagine that their winning percentage is really, really high," said Adam Isacson of the Washington Office on Latin America, a human rights advocacy group. "Whatever reputation they lose from episodes like this, their profit margins are still high enough to make it work. Otherwise people wouldn't pay."

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