SAN ANTONIO — A tractor-trailer that ended up in San Antonio with more than 50 dead or dying migrants passed through a federal immigration checkpoint inside the United States without being inspected, a top Mexican official said on Wednesday.
The truck crossed the checkpoint, operated by the Border Patrol, shortly before 3 p.m. on Monday as it drove north along Interstate 35 from the border region, the official, Francisco Garduño Yáñez, the head of Mexico’s National Institute of Migration, said at a news conference that featured images of the truck and its driver at the checkpoint.
The Mexican official also said that the rig had driven by a Border Patrol station in the town of Cotulla; that station does not operate a highway checkpoint.
The truck stopped roughly three hours later along a desolate road just off the highway, with the people inside either already dead or struggling to stay alive.
A young girl managed to climb out and cry for help.
“I didn’t get her name or think to ask where she came from,” said Roberto Quintero, who came upon the truck and called 911. “She just kept hanging on my arms, screaming, ‘Help me, help me,’ in Spanish.”
Officials said on Wednesday that at least 53 of the 64 people inside, men, women and some children who came from countries including Mexico, Honduras, Guatemala and El Salvador, died from the extreme heat inside the truck, which did not have any working cooling system on a day that temperatures topped 100 degrees. Several others were still being treated in local hospitals.
Gov. Greg Abbott, citing the failure of the federal checkpoint to detect the people being smuggled inside the tractor-trailer, announced that he had ordered the Texas State Police to create their own checkpoints to inspect trucks. He did not say what those inspections would entail or what portion of trucks would be stopped.
The governor also said that Texas police officers would increase their searches for stash houses that hide migrants and so-called cloned vehicles, which are used by smugglers but made to look legitimate. Officials have said the San Antonio truck had been disguised in that way.
Federal immigration officials have claimed success at capturing migrants seeking to enter the country illegally and have cited the use of audio and video surveillance and a network of vehicle checkpoints at the border and miles away from it.
But the fact that a tractor-trailer hauling scores of migrants could elude detection underscored just how difficult such interdiction is, particularly amid the seemingly endless stream of truck traffic up and down the commercial corridors linking the United States and Mexico.
A spokeswoman for Homeland Security Investigations declined to comment on how the tractor-trailer, which had Texas plates, smoothly passed through a federal checkpoint in Encinal, Texas, about 40 miles from the border.
But current and former officials said that most drivers pass through without being subjected to a thorough inspection, both because of legal limits on police searches and the sheer volume of truck traffic. Roughly 20,000 trucks pass through the corridor from Laredo to San Antonio every day.
“We know vehicles make it through,” said Jack Staton, a former senior executive with Homeland Security Investigations, a division of the Department of Homeland Security, which also includes the Border Patrol.
“They don’t have the staffing, resources and capabilities to check every single truck,” he said. “They search if they have suspicion of illegal activity. If they don’t, they let the vehicle go. They make sure traffic moves.”
Gov. Abbott’s announcement of the new checkpoints comes a little more than two months after he briefly introduced a similar strategy near international crossings, directing the state police to conduct vehicle safety checks of all commercial trucks arriving from Mexico. The universal truck inspections snarled traffic and caused economic damage both in Mexico and in Texas.
State police officers are not legally permitted to make universal inspections of vehicles for hidden people or other contraband, areas that are under the jurisdiction of the federal government, and so the officers were looking for violations of safety regulations for vehicles. The effort, in April, resulted in many unsafe trucks being taken off the road, but few if any discoveries of contraband or people being smuggled.
Federal border agents are also limited in the searches they conduct. “They have to have suspicion or reason to believe there is illegal activity,” Mr. Staton said.
The Border Patrol operates more than 100 checkpoints, most of them along highways and secondary roads that are 25 to 100 miles from the southern and northern borders.
As vehicles approach a checkpoint, agents ask only some of them to stop, and typically ask occupants whether they are U.S. citizens or residents to identify people who are potentially deportable. Agents may walk around the vehicles they stop to conduct a visual check. If they are suspicious of illegal activity or alerted by sniffer dogs of possible illicit cargo, the agents send the vehicles to secondary inspection.
From the 2016 through 2020 fiscal years, the Border Patrol apprehended about 35,700 potentially removable people at checkpoints and made about 17,970 drug seizures, according to agency data.
Truckloads of migrants have been known to pass through the checkpoint at Encinal. Last week, agents there were beginning to conduct an inspection of a tractor-trailer when the driver attempted to flee. After the vehicle crashed, dozens of migrants were found huddled inside.
The appearance of the ill-fated truck in San Antonio on Monday did not initially draw attention in the industrial area where it had stopped. But soon those inside were struggling to get out.
Mr. Quintero was wrapping up his day at a trucking company nearby when around 5:45 p.m. a co-worker came in shouting for someone to call 911. Mr. Quintero came out to see the tractor-trailer parked just outside the company’s gate.
By the truck, he saw the girl of about 10 or 11 sitting on the pavement, pounding the ground and screaming for help. The smell coming from the truck’s open doors was powerful. He looked inside.
“All these people were in a pile like they were trying to get out,” he said in an interview. A man on the far side of the human pile coughed like he could not breathe and stood up briefly but appeared too weak to pull himself over the bodies, he said.
A man in a black shirt, whom Mr. Quintero took to be the driver, emerged from the roadside brush at a distance from the truck, talking on his cellphone. Several of Mr. Quintero’s co-workers chased after him, but he disappeared into a field, Mr. Quintero said.
The San Antonio police said they arrested a man identified as the driver in a field near the truck. On Wednesday, federal prosecutors charged the man, Homero Zamorano, 45, with one count of alien smuggling resulting in death.
Prosecutors said they matched Mr. Zamorano, originally from the border city of Brownsville, Texas, to surveillance video of the driver of the truck as it passed through a Border Patrol checkpoint. Mr. Zamorano had communicated about transporting the migrants with another man, Christian Martinez, 28, according to prosecutors, who charged Mr. Martinez with conspiracy to transport illegal aliens resulting in death.
The charges against both men could result in a life sentence or the death penalty.
Two other men with connections to the truck were charged on Tuesday with weapons possession after they were arrested on Monday at a home in San Antonio. Neither is a legal resident of the United States.
Officials have said that smugglers follow a well-worn pattern for bringing migrants into the country. Small groups cross the river on foot and are then brought to hide-outs often known as stash houses. When a large enough number have been assembled, they may be brought by car, van or large truck to major cities such as San Antonio, Los Angeles, Houston or Phoenix.
As they move further from the border, detection becomes more difficult.
It was not immediately clear where or precisely when the people found inside the truck in San Antonio had gotten aboard. The Mexican officials, in their news conference, said the truck might have driven from the Rio Grande Valley area of Texas.
“Just because it went through a Border Patrol checkpoint, that doesn’t mean it was loaded with aliens at that time,” said Jerry Robinette, a former special agent in charge for Homeland Security Investigations in San Antonio. “We know for a fact it is very common for aliens to be smuggled around the checkpoint and then they are married with a transport to take them further north.”
The border with Mexico and the criminal gangs that operate around it have been a focus of Republican politicians, even in states far away, who have blamed President Biden for the increasing number of people trying to cross.
This month in Florida, Gov. Ron DeSantis asked the state’s Supreme Court to impanel a statewide grand jury to investigate whether families, local governments and criminal organizations were conspiring to transport migrants to Florida. On Wednesday, the court granted his request.
In Texas, Mr. Abbott has poured police resources and billions of dollars in state funds into disrupting smuggling networks and has claimed credit for helping to apprehend hundreds of thousands of migrants along with large quantities of drugs. But the effort has not reduced the total number of crossings.
The border city of Eagle Pass, where Mr. Abbott held his news conference on Wednesday, has been a particular focus of the governor’s efforts. For months, concertina wire has lined the banks of the Rio Grande in areas of the city and National Guard troops have watched the shores.
Nevertheless, the area around Eagle Pass had by June become the top spot in the United States for illegal crossings from Mexico.
Oscar Lopez contributed reporting from Mexico City. Eileen Sullivan also contributed reporting.