SAN ANTONIO/MEXICO CITY: The suspected driver of a truck packed with dozens of migrants who died in sweltering heat during a smuggling attempt in Texas this week was charged in U.S. federal court on Wednesday with a single count of migrant smuggling resulting in death.

Homero Zamorano Jr, 45, a Texas native, was arrested on Monday near the scene of the incident after he tried to pose as a survivor of the tragedy, which left 53 migrants dead and ranks as the greatest loss of life ever from a single human trafficking incident in the United States.

If convicted, he could face a maximum sentence of life in prison or possibly the death penalty, the U.S. Justice Department said in announcing the charges.

Also detained as a co-defendant in the case on Wednesday was Christian Martinez, 28, who was arrested on Tuesday and was charged with one count of conspiracy to illegally transport migrants resulting in death.

Federal prosecutors said Martinez was linked to the ill-fated smuggling operation through communications with Zamorano detected between the two men after a search by investigators of Zamorano's mobile phone.

The tractor-trailor truck packed with migrants from Mexico, Guatemala, Honduras and El Salvador was discovered abandoned on Monday in a desolate, industrial area near a highway on the outskirts of San Antonio, Texas, about 160 miles (250 km) north of the U.S.-Mexico border.

Temperatures in the area that day had soared as high as 103 Fahrenheit (39.4 Celsius), and authorities called to the scene found no water supplies or signs of working air-conditioning inside the cargo trailer.

Officials described finding the rear door to the trailer ajar with "stacks of bodies" inside, many of them hot to the touch. Other victims were discovered on the ground nearby. It was not made clear from official accounts how the door opened.

According to radio dispatch audio from authorities who were first on the scene, no one inside the trailer was conscious and only about a dozen appeared at first to be breathing.

Two more men suspected of involvement in the ill-fated smuggling operation, both of them Mexican nationals, were charged on Tuesday in U.S. federal court with being illegal immigrants in possession of firearms.

Authorities said the pair - Juan Francisco D'Luna-Bilbao and Juan Claudio D'Luna-Mendez - were arrested when they were seen leaving a San Antonio residence listed on the Texas state vehicle registration of the tractor-trailer.

A federal judge in San Antonio has ordered them to remain in custody to face a preliminary hearing set for Friday.