The Department of Justice said Homero Zamorano, 46, of Pasadena, Texas, and Christian Martinez, 28, of Palestine, Texas, had been charged on counts including transporting and conspiring to transport migrants illegally resulting in death and transporting and conspiring to transport migrants illegally resulting in serious injury.
A conviction on the transportation counts linked to the deaths could result in life imprisonment, although prosecutors could seek the death penalty. The charges related to serious injury carry penalties up to 20 years in prison.
DOJ officials said Zamorano was found hiding in the brush near the vehicle. A search warrant on his cell phone found communications between the man and Martinez, who was later linked to the smuggling event.
Two other men, both Mexican nationals, were also indicted on charges of possessing a firearm while being in the U.S. illegally.
The truck at the center of the tragedy had been packed with 67 people and a survivor told The Associated Press smugglers had covered the floor with powdered chicken bouillon to throw off any security dogs at border checkpoints.
Fifty-three people, including three children, died in the incident, the deadliest smuggling operation gone wrong along the U.S.-Mexico border.
Authorities discovered the grizzly scene on June 27 — when temperatures topped 100 degrees during a heat wave — after a concerned citizen reported a dead body near the abandoned truck. Officials said later they found “stacks and stacks of bodies” inside the hot tractor trailer, which had no working air conditioner or water inside.
More than a dozen other migrants were taken to area hospitals suffering from heat stroke and heat exhaustion, and the survivors were “hot to the touch.”
Texas has seen record levels of migrant crossings from Mexico this year, and authorities say the crossings are on pace to hit more than 2 million this year.