Texas Man Pleads Guilty to Human Smuggling Charges in San Antonio Tractor-Trailer Tragedy That Killed 53 Migrants

Christian Martinez, 29, will face a maximum penalty of life in prison at his sentencing next year, according to authorities

A Texas man pleaded guilty to his role in a human smuggling and trafficking operation that resulted in the deaths of 53 migrants, who were trapped inside a sweltering tractor-trailer in San Antonio last year.

Christian Martinez, 29, of Palestine, Texas, pleaded guilty to multiple charges related to the crime, the United States District Attorney’s Office for the Western District of Texas said in a press release shared on Wednesday.

According to the district attorney's office, “Martinez 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.”

Martinez — scheduled to be sentenced on Jan. 4, 2024 — faces a maximum penalty of life in prison, the district attorney's office noted.

According to the release, Martinez and 47-year-old co-defendant Homero Zamorano Jr. — the driver of the tractor-trailer — were initially charged on July 20, 2022. In total, four men were indicted by a federal grand jury in San Antonio, PEOPLE previously reported.

At the time of the "horrific tragedy," the San Antonio Police Department shared details of what occurred when authorities were first called to the scene.

During a live press conference via Facebook, Chief William P. McManus said that police received the first call at 5:50 p.m. local time from an employee working at a nearby building, who "heard a cry for help" and "came out to investigate." When approaching the truck, he saw the "partially open" door and found 46 dead migrants inside.

Related: San Antonio Fire Chief Details Gruesome Scene After 46 People Found Dead in Trailer: 'Stacks of Bodies'

After a team of fire trucks, police and emergency personnel responded to the scene at the 9600 block of Quintana Road, 16 people — 12 adults and four children — were rushed to hospitals before the death toll ultimately rose to 53.

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Two were admitted to University Hospital and at least five were taken to Baptist Medical Center, PEOPLE confirmed at the time.

Related: Family of 6, Including Trapped Baby, Saved from Indiana House Fire: 'Please Don't Drop Her'

"The patients that we saw were hot to the touch," Chief Hood said of the victims during the press conference. "They were suffering from exhaustion, no signs of water in the vehicle,” adding that there was no working air conditioning unit.

"We're not supposed to open up a truck and see stacks of bodies in there," he continued. "None of us come to work imagining that."

"This is nothing short of a horrific tragedy," San Antonio mayor Ron Nirenberg added at the time. "Our job is not to ask why. Our job is to ask how we can help. That's why you're seeing medical assistance. As far as the federal investigation goes, that's in the hands of the feds. I'm sure there will be more questions and hopefully some answers as we move forward."

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