A Texas man pleaded guilty last week to charges stemming from the deaths of 53 unlawful migrants who died from heat exhaustion after being left in a trailer near San Antonio.

The U.S. Attorney’s Office of the Western District of Texas said that Christian Martinez, 29, pleaded guilty to one count of conspiracy to transport illegal aliens resulting in death, one count of conspiracy to transport aliens resulting in serious bodily injury and placing lives in jeopardy, one count of transportation of illegal aliens resulting in death, and one count of transportation of illegal aliens resulting in serious bodily injury and placing lives in jeopardy.

The initial indictment from July 2022 alleged that Martinez drove Homero Zamorano Jr., a co-defendant in the case, to San Antonio to pick up an empty tractor-trailer that was later used to stow the unlawful migrants, according to the U.S. Attorney’s Office.

At least 66 unlawful migrants, including eight children and one pregnant woman, were loaded into the trailer.

Zamorano then allegedly abandoned the trailer, leaving the migrants inside. The trailer reportedly had no functioning air conditioning unit, and none of the people inside were able to exit. It was discovered by authorities on June 27, 2022. Many of the unlawful migrants, whose ages ranged from 13 to 55, suffered from heat-related illnesses, and 53 ultimately died, according to WFAA.

The incident, which is one of the deadliest smuggling incidents in U.S. history, resulted in a federal investigation by Homeland Security. Riley Covarrubias-Ponce, Felipe Orduna-Torres, Luis Alberto Rivera-Leal, and Armando Gonzales-Ortega were also indicted in connection with the deadly event.

Martinez is currently scheduled to be sentenced on January 4, 2024. He could receive up to life in prison for his crimes.

As previously reported by The Dallas Express, Texas officials have been sounding the alarm for months over the marked increase in smuggling operations transporting unlawful migrants into the United States.

Kinney County Sheriff Brad Coe told the U.S. House Committee on Homeland Security back in March that his deputies apprehended 741 human smugglers in 2022.

“That’s a huge increase from calendar year 2021 when we apprehended 169 human smugglers,” said Coe, per Fox News. “We are currently on track right now to exceed 900 smugglers for the year.”