An autopsy performed by Webb County Medical Examiner Dr. Corinne Stern on the 29-year-old woman from Mexico determined that hyperthermia — commonly known as heat stroke — was responsible for her death. Stern told CBS News: "I believe that the remaining individuals probably all succumbed to heat stroke as well, but their exams are not completed at this time, so I will not rule on their cause and manner yet." Temperatures in Laredo reached 97 degrees Sunday afternoon.
On Monday, a seventh victim turned up dead beside the tracks in an area southwest of San Antonio — roughly 150 miles from where the other six had been found in Laredo. According to Bexar County Sheriff Javier Salazar, investigators believe the train departed from Del Rio, Texas, then divided at a junction near San Antonio — one section heading to Laredo and the other toward Houston. Investigators were led to the seventh victim in part because a sensor on one of the containers had triggered an alert indicating it had been opened near that location, according to CBS News. Salazar noted that those containers have no mechanism allowing them to be opened from within.
"At this point, the prevailing theory is that he's a resident of Mexico that was among that group that was being smuggled into the country in one of these shipping containers," Salazar told ABC News.
Homeland Security Investigations and the Texas Rangers are also participating in the inquiry, according to ABC News. ICE told CBS News it is treating the deaths as a potential human smuggling incident.
San Antonio police had actually been alerted to the situation the day before, when an out-of-state relative of one of the victims called to report receiving a distress message from someone trapped in the container who said the heat had become unbearable, according to CBS News. The responding officers came up empty-handed during that initial search, but once news broke of the Laredo deaths, they went back to the area and combed the tracks until the seventh body was recovered.
In a statement cited by the Los Angeles Times, Union Pacific $UNP expressed grief over the deaths and said it has been cooperating fully with the law enforcement investigation.
