Mexican nationals among immigrants crammed inside sweltering truck
Twenty-five of the migrants found inside a sweltering tractor-trailer found parked outside a Texas Walmart in which 10 people died were Mexican, officials have said.
The Mexican foreign ministry said that based on interviews by consulate personnel and contact with local authorities, "we can say that of the 10 people who lost their lives ... four were of Mexican nationality".
The statement added that of the 29 people taken to hospital, 21 are Mexican. Some of the others inside the truck were from Guatemala.
As many as 90 people are thought to have been crammed inside.
The man charged with driving the rig has appeared in federal court in San Antonio.
James Matthew Bradley Jr, 60, faces charges of illegally transporting immigrants for financial gain, resulting in death. The judge explained to Bradley that he could face the death penalty, if convicted.
In the federal complaint, Bradley told authorities he did not realise anyone was inside the 18-wheeler.
Bradley, of Clearwater, Florida, was detained ahead of another hearing on Thursday.
Many of the immigrants had hired smugglers who brought them across the US border, hid them in safe houses and then put them aboard the tractor-trailer for the ride northward, according to accounts given to investigators.
"Even though they have the driver in custody, I can guarantee you there's going to be many more people we're looking for to prosecute," said Thomas Homan, acting director of US immigration and customs enforcement.
Bradley told investigators that the trailer had been sold and he was transporting it for his boss from Iowa to Brownsville, Texas.
After hearing banging and shaking, he opened the door and was "surprised when he was run over by 'Spanish' people and knocked to the ground," according to the criminal complaint.
He said he did not call 911, even though he knew at least one passenger was dead.
Bradley told authorities that he knew the trailer refrigeration system did not work and that the four ventilation holes were probably clogged.
The truck was registered to Pyle Transportation of Schaller, Iowa.
Company president Brian Pyle said he had sold the truck to someone in Mexico and that Bradley was supposed to deliver it to a pick-up point in Brownsville.
Mr Pyle said: "I'm absolutely sorry it happened. I really am. It's shocking. I'm sorry my name was on it (the truck)."
He said he had no idea why Bradley took the roundabout route he described to investigators.
Bradley told authorities that he had stopped in Laredo - which would have been out of his way if he were travelling directly to Brownsville - to get the truck washed and detailed before heading back 150 miles north to San Antonio. From there, he would have had to drive 275 miles south again to get to Brownsville.
"I just can't believe it. I'm stunned, shocked. He is too good a person to do anything like this," said Bradley's fiancee, Darnisha Rose of Louisville, Kentucky.
"He helps people, he doesn't hurt people."
One passenger described a perilous journey that began in Mexico, telling investigators he and others crossed into the US by raft, paying smugglers 12,500 Mexican pesos (about £540), an amount that also bought protection offered by the Zeta drugs cartel.
They then walked until the next day and rode in a pick-up truck to Laredo, where they were put aboard the tractor-trailer to be taken to San Antonio. The passenger said he was supposed to pay the smugglers 5,500 dollars (£4,220) once he got there.
Bradley told authorities that when he arrived in San Antonio, nobody met the tractor-trailer. But one passenger said six black SUVs were waiting to pick up the immigrants and were full in a matter of minutes. San Antonio police said CCTV footage showed vehicles picking up some of the immigrants.