Last month, 53 died and nearly a dozen others were hospitalized for heat-related conditions after they were found inside a semi-truck in San Antonio.
According to The Texas Tribune, Homero Zamorano Jr. And Christian Martinez face charges of transporting undocumented migrants in a way that resulted in serious injury, death and the jeopardizing of lives.
A federal grand jury also indicted Juan Claudio D'Luna-Mendez and Juan Francisco D'Luna-Bilboa, for one count each of possession of a firearm while unlawfully present in the United States. The men, both Mexican Nationals, have remained in federal custody since their arrest in June. The Department of Homeland Security is leading the federal investigation. Secretary Alejandro Mayorkas spoke to CBS's face the nation earlier this month.
"Our homeland security investigations is the lead federal agency investigating what occurred and working with the United States attorney's office in the prosecution of thus far four individuals who have been charged with that heinous crime," said Mayorkas.
If convicted, Zamorano and Martinez could face the death penalty while Mendez and Bilboa are facing up to 10 years in prison.
Attorneys for all four have not yet responded to a request for comment.
