SAN ANTONIO (AP) — Two smugglers convicted of federal charges in connection with the deaths of 53 migrants found in the back of a sweltering tractor-trailer in Texas in 2022 face up to life in prison when they are scheduled to be sentenced Friday.

Felipe Orduna-Torres and Armando Gonzales-Ortega are to be the first of several defendants sentenced in the San Antonio tragedy, which remains the nation’s deadliest human smuggling attempt across the U.S.-Mexico border. A jury convicted the men in March of being part of a human smuggling conspiracy that resulted in death and injury.

Prosecutors described Orduna-Torres as the leader of the smuggling operation inside the U.S. and Gonzales-Ortega as his top assistant.

The immigrants had come from Guatemala, Honduras and Mexico and had paid between $12,000 and $15,000 each to be smuggled into the United States, according to an indictment in the case. They had made it as far as the Texas border city of Laredo when they were placed into a tractor-trailer with broken air conditioning for a three-hour drive to San Antonio.

As the temperature rose inside the trailer, those inside screamed and banged the walls of the trailer for help or tried to claw their way out, investigators said. Most eventually passed out. When the trailer was opened in San Antonio, 48 people were already dead. Another 16 were taken to hospitals, where five more died. The dead included six children and a pregnant woman.

Investigators said the Orduna-Torres and Gonzales-Ortega worked with human smuggling operations in Guatemala, Honduras and Mexico, and shared routes, guides, stash houses, trucks and trailers. Orduna-Torres provided the address in Laredo where they would be picked up, and Gonzalez-Ortega met them there.

Five other men previously pleaded guilty to felony charges in the smuggling case, including the truck driver Homero Zamorano Jr., who was found hiding near the trailer in some bushes. Zamorano faces up to life in prison when sentenced in December. The other defendants are scheduled to be sentenced later this year.

The incident is the deadliest among tragedies that have claimed thousands of lives in recent decades as people attempt to cross the U.S. border from Mexico. Ten immigrants died in 2017 after they were trapped inside a truck parked at a Walmart store in San Antonio. In 2003, the bodies of 19 immigrants were found in a sweltering truck southeast of San Antonio.