Four Mexican nationals have been arrested for their alleged involvement in the deaths of 53 migrants found abandoned in a tractor-trailer in the scorching Texas summer last year, the US Justice Department said on Tuesday.

The four men — Riley Covarrubias-Ponce, Felipe Orduna-Torres, Luis Alberto Rivera-Leal and Armando Gonzales-Ortega, were arrested in Texas on Monday, said authorities.

They have been charged with conspiracy to transport immigrants resulting in death, serious bodily injury and placing lives in jeopardy.

If convicted, each will face a maximum penalty of life in prison.

A fatal scheme

A federal grand jury indictment unsealed on Tuesday revealed details of a "patchwork association" of smugglers that allowed them to "consolidate costs, spread out risk and operate profitably." 

According to the indictment, the migrants paid the men up to $15,000 (€13,699) each to be smuggled across the US border. The fee would cover up to three attempts to get into the country.

Each migrant was given a code word to provide at various checkpoints in order to indicate that they were paid "customers" of the smuggling arrangement.

One of the survivors said that the smugglers smeared chicken bouillon on the truck's floor to throw off any scent to the dogs at a US Border Control checkpoint.

"Tragically, 53 people who had been loaded into a tractor-trailer in Texas and endured hours of unimaginable cruelty lost their lives because of this heartless scheme," Attorney General Merrick Garland said in a statement.

What is the background of the tragedy?

In June 2022, the 53 people, including eight children, died of dehydration and heat stroke in San Antonio after they were shut inside a truck with no water on a day when temperatures rose to 39.4 degree Celsius (103 degree Fahrenheit).

Eleven of the migrants in the truck survived. The victims were from Mexico, Honduras, Guatemala and El Salvador.

Authorities said that the four Mexican men arrested Tuesday were aware that the truck's air-conditioning unit was malfunctioning and that the migrants would be trapped in the sweltering three-hour ride from the border city of Laredo to San Antonio.

The driver and another man were arrested shortly after the truck was found. They were charged with smuggling resulting in death and conspiracy.

A survivor recounted that soon after the truck left Laredo the trapped migrants started crying for water. Some took turns to breath via a single hole while others pounded the walls and yelled for the driver's attention.

ns/wd (AP, AFP)