A Texas truck driver charged in the deaths of 53 migrants who rode in a sweltering tractor-trailer with no air conditioning pleaded guilty Thursday over the 2022 tragedy that became the nation’s deadliest smuggling attempt across the U.S.-Mexico border.

Homero Zamorano Jr. pleaded guilty in federal court in San Antonio to one count of conspiracy to transport aliens resulting in death, causing serious bodily injury, and placing lives in jeopardy; one count of transportation of aliens resulting in death; and one count of transportation of aliens resulting in serious bodily injury and placing lives in jeopardy.

The 48-year-old could face a maximum sentence of life in prison, the Justice Department announced. Zamorano is scheduled to be sentenced on April 24.

Mark Stevens, Zamorano’s attorney, said in an email that he was unable to comment on a pending case.

Four Mexican nationals were also arrested in the case in 2023. And in August, a suspect arrested in Guatemala was charged with helping coordinate the smuggling attempt. U.S. authorities said they would seek the extradition of Rigoberto Román Miranda Orozco, who is charged with six counts of migrant smuggling resulting in death or serious injury. Authorities alleged he is connected to four Guatemalan migrants in the trailer, three of whom died, and faces up to life in prison if convicted.

According to the indictment against Miranda Orozco, the smugglers had forced the migrants to give up their cellphones before getting inside the trailer, leaving them no way to call for help. An unknown powder was spread around the trailer to prevent the smell of human cargo from being detected by patrol dogs at border inspection stations.

When the trailer was opened in San Antonio, 48 migrants were already dead. Another 16 were taken to hospitals, where five more died. President Joe Biden called the tragedy “horrifying and heartbreaking.”

Those who died were seeking better lives. News of the trailer full of bodies was met with horror in cities and villages accustomed to seeing their young people leave, trying to flee poverty or violence in Central America and Mexico.

Authorities allege that the men worked with human smuggling operations in Guatemala, Honduras and Mexico, and shared routes, guides, stash houses, trucks and trailers, some of which were stored at a private parking lot in San Antonio.

Migrants paid the organization up to $15,000 each to be taken across the border. The fee would cover up to three attempts to get into the U.S.

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 migrants died in 2017 after they were trapped inside a truck parked at a Walmart in San Antonio. In 2003, the bodies of 19 migrants were found in a sweltering truck southeast of San Antonio.