(CNN) – Four people have been arrested and charged following the deaths of 53 immigrants in what an Internal Security Investigating Agent called the deadliest human trafficking case in U.S. history.
Immigrants were found in poor condition inside a van in San Antonio on Monday after an employee at a nearby building heard screams for help.  More than a dozen people were found alive inside the tractor-trailer and were treated for heat-related conditions, according to San Antonio authorities.
Homero Zamorano Jr., 45, originally from Brownsville but living in Pasadena, Texas, was arrested Wednesday on charges of allegedly involved in human trafficking resulting in death, according to a U.S. Department of Justice press release. .  According to public records, Zamorano has a long criminal record dating back to the 1990s.
Christian Martinez, 28, who was arrested Tuesday in Palestine, Texas, has been charged with conspiracy to smuggle undocumented migrants, resulting in his death, the Justice Department said.
If convicted, both Zamorano and Martinez will face life in prison or the death penalty.  CNN could not determine whether Zamorano or Martinez have a lawyer.
When police arrived at the scene Monday, they found several people inside the tractor-trailer, some on the ground and in a nearby brush, “many of them dead and some of them incompetent,” according to a DOJ statement.
“SAPD officers were led to locate a man, later identified as Zamorano, who was spotted hiding in the brush after trying to escape. Zamorano was arrested by SAPD officers,” the statement said.
The Laredo Sector Border Patrol also provided Internal Security Investigators with surveillance videos showing the tractor trailer passing through an immigration checkpoint, according to the announcement.  The driver appeared to be wearing a black striped shirt and hat.
“HSI agents confirmed that Zamorano matched the person from the surveillance video and wore the same clothes,” the statement said.
An investigation has revealed that there were communications between Zamorano and Martinez regarding the smuggling incident, according to the announcement.
Two other people, Juan Claudio D’Luna-Mendez and Juan Francisco D’Luna-Bilbao, are charged with “illegal possession of an alien weapon in the United States,” according to criminal charges filed Monday.  Authorities were able to locate the men after responding to the incident in a van, according to the affidavit.
D’Luna-Mendez’s lawyer said he was not commenting on any pending cases.  CNN contacted D’Luna-Bilbao’s lawyer and received no response.


There is no water or AC power in the trailer, said the fire chief 
The semi-trailer-trailer refrigerator had no visible air conditioning unit operating and there was no sign of water inside, San Antonio Fire Chief Charles Hood told reporters Monday.  It is not clear how long the people in the truck were dead, he said.
High temperatures in the San Antonio area on Monday ranged from highs in the 1990s to low 100s, according to the National Weather Service.
“None of these people were able to get out of the truck,” Hood said.  “So they were still there, waiting for help when we arrived … which just means they were too weak – a weakened state – to go out and help themselves.”
Craig Larrabee, San Antonio Homeland Security Investigator, who acts as the lead officer, described it as “the worst case of human trafficking in the United States.”
“In the past, smuggling organizations were mothers and smugglers. Now they are organized and linked to cartels. So you have a criminal organization that does not care about the safety of immigrants. They treat them as a commodity and not as people.”  Larrabee told CNN in a telephone interview.
The revelation came as U.S. federal authorities launched what they described as an “unprecedented” operation to disrupt human trafficking networks amid an influx of immigrants to the U.S.-Mexico border.
Business owners in the area where the trailer was found told CNN they were shocked.
“They were people, it was awful,” said Israel Martinez, 68, co-owner of USA Auto Parts.  “We (immigrants) are coming to this country for a better life and yesterday reminded many of us that, unfortunately, some of us succeed, but many others do not.”