Police are digging into how six migrants, including a teenager, died inside a freight car that arrived at a rail yard in Laredo, Texas, last week.

The discovery of a potential seventh body and a recent arrest connected to a federal smuggling investigation in the region could hold the keys to explaining the tragedy.

On May 10, a Union Pacific employee inspecting a train car at a company facility in Laredo discovered six bodies.

Preliminary investigations indicate that the group was compromised of a woman and two men from Mexico, as well as three men from Honduras, all of whom died of overheating inside the train car. Their ages ranged from 14 to 56.

“We are demanding justice for these lives lost,” Laredo Mayor Victor Treviño said at a news conference Thursday. “It doesn’t matter where they came from.”

A day after the initial six bodies were found, a seventh set of remains was discovered near railroad tracks in Bexar County, nearly 150 miles away, where investigators discovered a man’s body with a Mexican ID.

Authorities believe the body may be linked to the Laredo deaths, though no official connection has been announced between the cases.

“On these trains, there is a censor on some of the containers that alerts whenever a container’s opened,” Bexar County Sheriff Javier Salazar told reporters on Monday. “Once those bodies were found in Laredo, they came back to this location here and started patrolling up and down the railroad tracks until such time that they found him.”

A family member identified the man to Fox San Antonio as 49-year-old Nereo Aguilar Garcia.

The train had previously been in Del Rio, Texas, to the west of San Antonio. It then split up its cars closer to the city, with some heading south towards Laredo, the sheriff said.

The same day the seventh body was found, federal officials with Homeland Security Investigations executed a search warrant near the U.S.-Mexico border in Del Rio as part of a human smuggling case.

During the search, three people ran from the house, waded into the Rio Grande River, and fled into Mexico, according to court documents seen by The Independent.

At the house, officers arrested Mayra Huerta on suspicion of harboring undocumented immigrants.

Huerta told HSI agents she lived at the house with her husband and her husband’s son and nephew, all of whom are Mexican nationals without legal authority to be in the U.S. The Independent has contacted Huerta’s attorney for comment.

Sources told Fox San Antonio the men are believed to be connected to the train smuggling deaths.

Agents found weapons and nearly $53,000 in cash during the raid, according to the station.

A spokesperson for the Bexar County Sheriff’s Office told The Independent that HSI is now leading the investigation.

“HSI is actively investigating this case as a potential human smuggling event with assistance from the Laredo Police Department and Texas Rangers,” a spokesperson from Immigration and Custom Enforcement told The Independent.

“Due to the ongoing investigation, no additional information can be released at this time,” the person said.

“Union Pacific is saddened by these incidents and continues to work closely with law enforcement agencies, leading the investigation,” the company said in a statement to The Independent.

Investigators believe one of the people inside the train sent a text message to a relative the day before the first set of bodies were discovered saying the train was “really, really hot” inside. Highs in Laredo topped 90 degrees Fahrenheit that day.

The family member then called the San Antonio Police Department, whose officers were unable to locate car in question, the sheriff of Bexar County .

Treviño, the Laredo mayor, on Thursday urged migrants seeking a better life in the U.S. to pursue safe and legal pathways.

“Smugglers do not care about your safety and will place you in a life-threatening situation without hesitation,” he said. “No opportunity is worth your life. We urge you to seek legal and safe pathways.”

The border has been home to a series of gruesome tragedies resulting from human smuggling in recent years.

In 2022, 53 migrants — including six children — were found dead inside a tractor-trailer that had no cooling system on the outskirts of San Antonio.

President Donald Trump’s anti-immigration agenda has also seen U.S.-Mexico border crossings plummet, though illegal crossings continue.

As The Independent previously reported, the U.S. has long enacted a “prevention through deterrence” border strategy that uses security build-up at popular crossing points to funnel migrants towards more treacherous, remote areas, in the hopes that the danger of such crossings will deter future efforts to illegally immigrate.

The Trump administration has revived construction on the president’s signature border wall, a project critics accuse of fueling migrant deaths, desecrating cultural sites, and harming the environment.