Tyrone M. Williams had barely been on the road for an hour when he heard the banging and cries coming from the trailer of his 18-wheeler.

It was almost midnight on May 13, 2003, and Williams, a dairy trucker, was carrying human cargo. Earlier that night, human traffickers in southeast Texas had loaded dozens of undocumented immigrants into the rear compartment. For a fee of $7,500, Williams had agreed to drive them 120 miles north, through a Border Patrol checkpoint.

The plan went awry when two of the smugglers who were supposed to rendezvous with Williams farther up the highway were detained. Williams was ordered to take his passengers all the way to Houston, an additional 200 miles.

Driving through the hot Texas night, Williams never turned on the refrigeration unit in his dairy truck. As the temperature inside the cramped trailer rose to an unbearable 173 degrees, the people inside grew desperate, kicking holes in the walls, clawing at the insulation and screaming for help.

Hours later, when Williams finally opened the doors on a stretch of highway in Victoria, Tex., 19 people inside were dead of dehydration, overheating and suffocation.

The incident has been called the nation’s deadliest and most thoroughly documented human trafficking case, and it received renewed attention on Sunday, after authorities discovered a strikingly similar scene in San Antonio.

At least 39 people were found packed into a sweltering tractor-trailer in a Walmart parking lot, appearing to have been loaded like cargo into the tight container without working air conditioning. Eight men died inside, and a ninth died later at the hospital. Many others were critically overheated, with some believed to have suffered brain damage. Survivors told investigators that as many as 100 people were crowded in the truck’s trailer at one point, as The Washington Post reported. The driver has been arrested and is expected to be charged in federal court.

Police found a truck July 22 near a Walmart in San Antonio that contained at least 39 people suspected of crossing the border illegally. Eight of the people died at the scene, and two died later in a hospital. (Monica Akhtar/The Washington Post)

Authorities said it bore all the hallmarks of the immigrant smuggling operations that are common in that part of the country. Officials with the U.S. Department of Homeland Security have indicated smuggling by truck is on the rise, with several operations uncovered in Texas in recent months.

Investigators have revealed little about the chain of events that led to the deaths in San Antonio, but the 19 immigrant deaths in Victoria in 2003 highlight the perils of traveling by truck to evade border agents, as well as the complex networks that smuggle people into the country.

According to court documents from the case, a man and woman who led a smuggling operation in southern Texas had been recruiting American truck drivers to carry undocumented immigrants through checkpoints near the border, paying thousands of dollars for short drives. Court papers say they were especially interested in non-Hispanic drivers with out-of-state licenses because they were less likely to be scrutinized by authorities.

Tyrone M. Williams fit the bill: He was a native of Jamaica who had immigrated legally to the United States, and he drove a truck licensed in New York. On top of that, he ran his own trucking business, and his vehicle was refrigerated. He had recently transported dairy products to from New York to Texas, so he had legitimate reasons to be in the state.

How exactly the smugglers found Williams is not clear, but he started driving for them in the spring of 2003, according to court records. In May of that year, he agreed to pick up a group of undocumented immigrants from Harlingen, Tex., near the Mexico border, drive them through a checkpoint in Sarita, Tex., then drop them off with other members of the smuggling operation in Robstow, Tex. The trip was expected to take less than two hours, and Williams was to be paid $7,500.

Williams and a female companion arrived in Harlingen late at night on May 13, 2003. They stayed in the cab of the truck while human traffickers loaded 74 people into the trailer and locked the doors. Instead of keeping the interior at a cool 55 degrees, as the smugglers had advised him, Williams turned off the refrigeration unit entirely, probably to appear more convincing to inspectors. When the truck reached the checkpoint in Sarita, he told an agent that his trailer was empty and that he was headed to Houston to pick up produce. The agent waved him through without trouble.

The remaining 60 miles should have been easy. But shortly after pulling out of the checkpoint, Williams got a call from the head of the operation: the smugglers who were supposed to pick up the immigrants in Robstown had been detained. Instead of stopping in Robstown, Williams was told to drive all the way to Houston — some 200 miles away.

Around that time, Williams and his companion, Fatima Holloway, started to hear the clamor from the compartment behind them. A fellow trucker flagged them down and said human arms were protruding from holes in the trailer walls. Holloway pleaded with Williams to let the passengers out, but Williams drove for at least another hour before stopping in a small town. He passed them several bottles of water through the holes but otherwise ignored their cries for help. At one point, worried about the damage to his rig, he called the smugglers to demand more money.

Williams drove for another 90 minutes through southeast Texas before stopping again, this time at a truck stop in Victoria, Tex., 100 miles outside Houston. There, a witness spotted him passing water bottles through the holes in the trailer and alerted a clerk, who called police. Williams unhooked the trailer and sped off into the night.

When authorities arrived at the truck stop, they found a scene of unspeakable agony and death. The U.S. Court of Appeals for the 5th Circuit described it in grim detail in a 2010 ruling:

There were several dead bodies on the ground by the trailer doors. Bodies, both dead and living, were stacked in a pile in the trailer. Some of the aliens were standing behind the pile. The aliens were stripped down to their underwear and were sweating. They had clawed at the foam on the inside of the trailer, and the trailer smelled of vomit, urine, feces, and blood.

Seventeen people riding in Williams’s truck had died inside from dehydration, overheating and suffocation. Two died later at the hospital of the same causes. A 5-year-old boy was among the victims.

Williams was arrested and indicted on dozens of counts, including conspiracy and harboring. Prosecutors sought the death penalty.

In court, survivors testified that they took off sweat-soaked clothes, pounded at the walls and gasped for air through the small openings they created as the temperature inside the trailer reached 173 degrees, the Associated Press reported in 2005. Some of them frantically tried to get the attention of passing motorists, pushing shoes through the holes to show they were in distress. Holloway testified that she and Williams could hear the passengers screaming “el nino, el nino,” referring to the 5-year-old dying behind them, according to the Los Angeles Times.

Williams argued he would have opened the doors if he had known the passengers were in serious danger, telling a judge, “I don’t kill people.” Prosecutors alleged he was aware of their suffering all along but did nothing. In 2011, after his case wound through the court system, Williams, then 40, was sentenced to nearly 34 years in prison without parole. Another 13 people were indicted in connection with the deaths. Most received sentences ranging from one year to 23 years in prison.

In May 2013, on the 10th anniversary of the 19 immigrants’ deaths, an emergency room worker who treated the victims told ABC 13 she was still haunted by the scene.

“If I knew then what I saw that night, I would have never gone into the medical field,” Mary Rose Garcia said. “There’s no way you can forget.”

Thomas Homan, the acting director of U.S. Immigration and Customs Enforcement, was among the agents who personally worked on the 2003 case. In a statement Sunday, he said the 19 immigrants died “as a result of the smugglers’ total indifference to the safety of those smuggled and the law.”

“By any standard,” he said, “the horrific crime uncovered last night ranks as a stark reminder of why human smuggling networks must be pursued, caught and punished.”

More from Morning Mix:

Pennsylvania police, hunting for stolen laptops, say they stumbled on $40 million bitcoin scam

Utah couple arrested after drugging heroin-addicted newborn to hide symptoms, police say

Fukushima’s melted nuclear fuel likely sighted in ghostly underwater images