Immigrants who survived a trip inside a big rig in which eight people were found dead in San Antonio this weekend told police as many as 180 to 200 people had been in the trailer at some point during the trip, according to court documents. >> Read more trending news A criminal complaint filed Monday against James Mathew Bradley Jr. also outlines the danger and cost of crossing the Texas-Mexico border illegally, including an expensive river crossing and protection payments to men with alleged ties to the notorious Zetas drug cartel. When authorities found the vehicle on the southwest side of San Antonio on Sunday, there were 39 people inside, including the eight dead. Two more died from their injuries after being taken to area hospitals for treatment. The immigrants, identified only by their initials, told investigators that they had paid thousands of dollars to enter the country. One told authorities he was traveling with seven relatives in a group of 24 people. He said he’d been held in a stash house in Laredo for 11 days before boarding the rig. “He stated when his group arrived at the tractor-trailer, there were already 70 people in the trailer and it was very hot,” the complaint said. Another immigrant told investigators that he was going to pay smugglers $5,500 when he arrived at his final destination in San Antonio. But even before, he was told by a smuggler that that people linked to the Zetas drug cartel would charge 11,000 pesos (about $622) for protection and another 1,500 pesos (about $85) to cross into the United States by raft at a deep section of the river. “The money was collected and his group crossed the river by raft in three trips,” the complaint said. One of the undocumented immigrants told federal investigators that “people had a hole in the trailer wall to provide some ventilation, and they started taking turns breathing from the hole.'f The victims “were very hot to the touch” and the “people were in this trailer without any signs of any type of water,” San Antonio Fire Chief Charles Hood said. Temperatures reached a searing 101 degrees in San Antonio on Saturday and didn’t drop below 90 degrees until after 10 p.m. Authorities said 39 people were in the truck when rescue workers arrived early Sunday. Four of the survivors appeared to be between 10 and 17 years old, ICE acting Director Thomas Homan said. Bradley was charged Monday with transporting immigrants in the U.S. illegally for 'commercial advantage or private financial gain.' The Associated Press reported that the charge could qualify for a death penalty sentence if Bradley is convicted. The Associated Press and the Cox Media Group National Content Desk contributed to this report.