A cross honoring Esequiel Hernandez Jr. stands on the place where he died in Redford, Tex. (Guillermo Arias/AP)

It was a cloudy afternoon in May 1997, on a desolate hill of rugged desert and alfalfa fields along the Rio Grande known as “El Polvo,” Spanish for dust. Esequiel Hernandez Jr., a high school sophomore who had just turned 18, ventured out with his herd of 43 goats near his family’s home, guiding them through the brush to graze. As usual, to protect his flock from wild dogs or coyotes, he carried with him his .22-caliber rifle.

In the distance, something moved. Approaching him were four heavily camouflaged U.S. Marines, armed with M-16s, looking for drug smugglers.

The encounter that followed would leave Hernandez, an American citizen, shot in the chest by a Marine corporal. He bled to death, receiving no medical aid. Military officials said the Marine team shot the teenager after he twice fired his rifle in their direction and was raising his gun for a third time, according to Washington Post coverage at the time. Relatives of Hernandez, along with the Texas Rangers who investigated the case, doubted that the teenager ever saw the hidden Marines.

While the circumstances of the shooting would be disputed for years, it spurred an immediate uproar and came to symbolize the dangers of an armed military presence on the border. By July of that year, following local protests, the Pentagon suspended military patrol of the border.

More than two decades later, Hernandez’s death has emerged in the national conversation once again this week, amid news that President Trump wants to send 2,000 to 4,000 National Guard troops to the southern border as part of his administration’s effort to crack down on illegal immigration and drug trafficking. Trump signed a presidential proclamation Wednesday directing the Department of Homeland Security and the Pentagon to coordinate with governors to send National Guard troops to the border with Mexico.

The details of the Guard’s mission are still unclear, including whether the troops will be allowed to carry guns.  Still, some critics argued that sending U.S. service members to the border would make the region more dangerous, not less. Some, like Rep. Beto O’Rourke (D-Tex.), invoked Hernandez’s death in his criticism of Trump’s plans. O’Rourke recounted the killing in a tweet Tuesday.

“This is what happens when we militarize the border,” O’Rourke wrote.

One resident of border town Presidio, Tex., Velva Saenz, told NPR this week that she went to school with Hernandez. Asked about the president’s plans to send troops to the border, the 37-year-old woman said that “because of what happened with … Esequiel, it kind of makes you think about it.”

“You know, we lived it with him,” Saenz added. “So it makes you think twice whether it’s safe or not.”

The 1997 killing marked the first time drug-fighting military troops had fired on a U.S. citizen since they had been deployed to the border in the 1980s, the Houston Chronicle reported at the time. It was also the first slaying of an American citizen by a military service member on U.S. soil since the 1970 Kent State University shooting, when Ohio National Guardsmen killed four college students during a demonstration.

The Marines had just arrived at the border a few days before the fatal shooting, which took place in Redford, Tex., more than 200 miles southeast of El Paso. It was a farming community of 100 people of mostly Mexican descent, an isolated desert area where rifles, like Hernandez’s, were a part of life.

When they came across Hernandez, the four Marines were wearing ghillie suits, a type of camouflage designed to resemble foliage, and had blackened faces. They spotted the young man from about 200 meters away, the Marine team leader said into his radio, according to transcripts that later became public and were played in a PBS documentary about the shooting.

“He’s heading towards us,” Cpl. Clemente Banuelos said. “He’s armed with a rifle, appears to be herding uh … some goats or something.”

“You should remain in your position,” a Marine command responded, “and try not to be seen, but you should know what to do.”

“We’re taking fire,” Banuelos said. Hernandez had shot from across a ravine, the Marines said. When he walked away, the camouflaged Marines followed him.

“As soon as he readies that rifle back down range, we’re taking him,” Banuelos said. From a distance, they tracked the teenager for about 15 minutes. Then, they “inexplicably” rushed toward him, a House report later said. According to the Marines, Hernandez then raised his gun toward them. Banuelos fired his weapon.

“Our Marines took him out,” one of the team members said on the radio.

He was only 300 yards away from his home when he was shot, Hernandez’s brother, Margarito Hernandez, told The Post at the time. His father was chopping wood outside when he heard what he thought was a gunshot. Shortly after the teenager was killed, his 11-year-old brother ran into Esequiel Hernandez’s bedroom and ripped a Marine recruiting poster from the wall, The Post reported. Hernandez had been thinking about joining the Marines.

Autopsy results would later contradict the Marines’ claim that Hernandez was facing them with his rifle when he was shot. The Marines gave conflicting accounts of the incident to investigators. Former Texas Ranger Capt. Barry Caver, who oversaw the investigation, told the San Antonio Express-News that he believed Hernandez never saw the group and that any shots he fired were random.

Jack Zimmermann, a Houston attorney and former Marine who defended Banuelos, disputed such accounts. “He looked right at them, raised his rifle deliberately, and shot twice at them. No one has ever contended he knew they were Marines, but he knew they were people,” he said, The Post reported.

More than a year later, a House report by Rep. Lamar S. Smith (R-Tex.), then chairman of the Judiciary Committee’s subcommittee on immigration and claims, found that “a series of failures” by the Justice and Defense departments led to Hernandez’s death. According to the report, the Border Patrol did not offer the Marines any training on civilian law enforcement or on local conditions.

Federal and state grand juries declined to indict any of the Marines. A Presidio County grand jury ruled that Banuelos was acting in self-defense when he shot Hernandez.

Ultimately, the federal government agreed to pay the family $1.9 million to settle claims against the Marine Corps and the department. But Margarito Hernandez, the slain teenager’s brother, told the Express-News that “there was no justice.”

“My mom never came out of shock,” Margarito Hernandez told the Express-News last year. “She died a few months ago. She never recovered.”

More than two decades later, Hernandez’s death continues to inform the way locals see the military’s presence at the border.

“We’re all suffering from post-traumatic stress syndrome that’s 20 years old,” Enrique Madrid, 69, a local activist and historian, told the Express-News. It’s something we’ll never forget.”

More from Morning Mix:

From crack cocaine to Mar-a-Lago: The unusual journey of the MyPillow man

Jared Leto’s really quick ‘hitchhike’ across America