According to court documents, the driver of a tractor-trailer carrying dozens of migrants died this week. He didn’t know that the trailer’s air conditioner had broken down. The trailer, which was found Monday in San Antonio, contained more than 50 victims.

Christian Martinez, one the men in this case, was allegedly found texting the suspect driver on Monday with a manifest of the truck and a location in Laredo (Texas).

According to a Texas federal court complaint, Martinez told an informant that Homero Zamorano Jr. was the suspect driver and that the air conditioner had stopped working.

Nestor Canales, a special agent in Homeland Security Investigations, describes a series text messages between Martinez and Zamorano that began around noon Monday.

Martinez was allegedly text messaged by Zamorano, who said that he went to the same place. According to the complaint, Martinez replied half an hour later with a GPS location in Laredo Texas.

Martinez sent Zamorano several text messages that afternoon. They included “Call me bro” (or “Wya bro”), which was believed to be an abbreviation of “Where are you at?”

Prosecutors claim that Zamorano was later discovered by police hiding in brush near an abandoned 18-wheeler, just outside San Antonio.

On Thursday, Zamorano (45) appeared before a federal court in San Antonio. He was charged with one count for alien smuggling that resulted in death. Martinez, 28 years old, is charged with one count for conspiracy to transport illegal aliens. This will result in his death.

Both men could face life imprisonment or death if convicted.

Two other men were also charged in the case, including Martinez and Zamorano. Prosecutors claim that the tractor-trailer registration led police to a San Antonio address. Two men were later arrested, Juan Claudio D’Luna–Mendez and Juan Francisco D’Luna–Bilbao. Both men are being charged with weapons violations by the authorities.

After being trapped in the trailer, 53 migrants from Mexico, Guatemala and El Salvador were killed. This makes it one of America’s most tragic human smuggling tragedies.