SAN ANTONIO >> Mexican government officials said today they were working to reunite families with some of the survivors of a failed human smuggling operation and had been assured by U.S. immigration officials that they would not question relatives about their legal status in the United States.

Ten immigrants, including seven from Mexico, died after a sweltering ride from the Texas border city of Laredo in a tractor-trailer without air conditioning on Sunday. Another of the dead was identified as being from Guatemala; two others were not publicly identified.

At least 29 immigrants survived, according to U.S. officials. Twelve remained hospitalized today in San Antonio.

The driver of the big rig, James Matthew Bradley Jr., waived a detention hearing that had been scheduled for Thursday and remained in federal custody, charged with illegally transporting immigrants for financial gain, resulting in death. Federal court records indicated a new hearing was set for Aug. 23, when Bradley was expected to a give video deposition. The 60-year-old Florida trucker could face the death penalty, if convicted.

Latin American diplomats worked, meanwhile, to confirm names of the dead and injured, most of who were not publicly identified.

The top Mexican diplomatic official in San Antonio said relatives of some of the immigrants didn’t even know their family members had left for the United States. Consular officials were working to notify families, repatriate bodies and arrange hospital visits for relatives of the survivors.

“We have to make sure everyone is informed and everyone knows where their children are,” said Reyna Torres Mendivil, the Mexican consul general for San Antonio.

U.S. immigration authorities assured her, she said, that any relatives escorted by consular officials on hospital visits would not be questioned about their legal status.

Thirteen immigrants were in federal custody, being held as material witnesses in the government’s case against Bradley, the U.S. Attorney’s office announced.

Their appointed attorney, Michael McCrum, said it was too early to know whether they would receive visas or be allowed to settle in the United States in consideration for their help.

“One of my concerns is that they begin to be treated as chips in a political game instead of real people who have been severely abused,” McCrum said.

It’s not clear how many immigrants in total were in the tractor-trailer. An unknown number fled once its doors were opened in a Walmart parking lot early Sunday, on foot or into six waiting black SUVs, according to a federal criminal complaint against the driver.

One victim, a 19-year-old who had been previously deported and was trying to get back to his family in Maryland, was identified as a Guatemalan national by diplomat Cristy Andrino.

Andrino told the AP that Frank Guisseppe Fuentes immigrated to the U.S. as a child, but was deported this past March.

Another of the dead was identified as Jose Rodriguez Aspeitia, 34, from the Mexican town of Palo Alto, Aguascalientes. A town spokesman told The Associated Press that Aspeitia had worked in construction there and had apparently spent time in the United States. Aspeitia was rescued from the tractor-trailer, but later died at a hospital.

An Aguascalientes state government official at the consulate told the AP that Aspeitia’s family was driving north to San Antonio, hoping to cross the border on humanitarian grounds.

Investigators have said they believe Bradley was part of a larger organization involved in human smuggling that authorities are trying to identify and dismantle.

Bradley had his commercial driving privileges suspended by Florida three months before Sunday’s deadly smuggling attempt, officials said. And court records show he had been repeatedly cited for violating federal motor carrier safety regulations in Iowa dating back to 1995. At least two of the tickets were for logging more hours than allowed.