SAN ANTONIO (AP) — Two individuals found guilty of federal charges related to the deaths of 53 migrants discovered in the back of a stifling tractor-trailer in Texas in 2022 are facing potential life sentences when they appear for sentencing on Friday.

Felipe Orduna-Torres and Armando Gonzales-Ortega will be the first among several defendants to receive their sentences for their involvement in the San Antonio incident, which stands as the deadliest attempt at human smuggling across the U.S.-Mexico border to date. In March, a jury found them guilty of participating in a human smuggling conspiracy that led to fatalities and injuries.

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

The migrants were from Guatemala, Honduras, and Mexico, and they had paid between $12,000 and $15,000 each to be brought into the United States, as indicated by the indictment. Their journey reached the Texas border city of Laredo, where they were loaded into a tractor-trailer with a malfunctioning air conditioning system for a three-hour trip 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.