Hidalgo County, Texas (CNN) From the sedan's back seat, Melba Coody watched as the mesquite-lined flatland of South Texas rushed by. About a century ago, she explained, her family owned all this property, as far as the eye could see.

Christine Molis, her hands on the wheel, knew that already, of course. It was a critical detail of the story her 76-year-old mother was about to retell, the story of what happened in this place -- the single event that, in their view, altered their family's destiny.

The narrative had always been there, in relatives' musings about what might have become of the family's wealth and influence if not for the killings so long ago of hundreds of Mexican-Americans by members of the vaunted Texas Rangers who took justice into their own hands

The saga -- known as La Matanza, or The Massacre -- had recently crept onto the public stage with a push for historical markers acknowledging the slayings, along with the era's anti-Mexican rhetoric and unequal treatment of Americans of Mexican descent in the border region.

Its underlying elements also seemed to be there in the latest headlines about securing the US-Mexico border in the age of President Donald Trump: the militia group detaining migrants in New Mexico, the US citizens asked for ID when a border agent in Montana heard them speak Spanish, the humanitarian crisis faced by migrant children detained in Texas and Trump's own racist tweets insisting Democratic congresswomen of color leave the United States if they don't like his policies.

The circumstances of the stories -- then and now -- are not the same. But all hinge on who's welcome in the United States and how to treat those who aren't. And for many descendants of those killed a century ago, the old stories -- often ignored in textbooks and unknown even by those with a firm grasp of US history -- may hold lessons for how to face today's challenges and ensure injustice doesn't again prevail.

It's why so many who trace their lines back to the early 20th-century horrors want to share the details of what happened right here in the Rio Grande Valley. "I tell my kids," Coody said as she guided her grown daughter on what would be a pivotal day in the younger woman's understanding of the family history. "I don't want them to forget this."

A cemetery that holds a dark secret

Dry leaves crackled underfoot and dogs barked in the distance as Coody lifted the gate's metal latch. Stepping inside, the elderly woman laid out the crux of the generations-old tale: Here -- on this very spot -- Coody's great-grandfather, Jesus Bazán, and her great-uncle, Antonio Longoria, were shot in the back and left to die on September 27, 1915.

Bazán, 67, and Longoria, 49, were US citizens and prominent landowners of Mexican heritage: Longoria was a US postmaster , a certified school teacher and an elected Hidalgo County commissioner; Bazán, even in old age, was known to help area farmers translate Spanish agricultural terms to English.

Jesus Bazán

Antonio Longoria

The men had traveled that day to the Texas Rangers camp at a nearby ranch to report some stolen horses, Coody said, repeating the story she learned as a girl and one now authorized by the Texas Historical Commission

The conversation at the Sam Lane ranch also included talk of so-called Mexican "bandits" -- a crude reference at the time to anyone whose roots traced south of the border, recalled Roland Warnock, then a 19-year-old cowboy at the ranch, in the 2004 documentary, " Border Bandits ." CNN was unable to reach descendants of the ranch's owners.

Bazán and Longoria left the ranch on horseback, the state record shows. Texas Ranger Captain Henry Ransom and two civilians followed them in a Ford Model T.

At some point along the road, a firearm barrel emerged from one of the car's windows. The gunman aimed at Bazán and Longoria, still riding up ahead.

He pulled the trigger.

The men's bodies hit the ground. Their horses galloped away. The Model T drove off. "Unfazed by the shooting," the official narrative goes, "it was reported that Captain Ransom returned to the campsite to take a nap."

Texas Rangers pose on October 8, 1915, while holding ropes tied to corpses.

The killings came at a time of turmoil in Texas. As the Mexican Revolution seethed to the south and Europe crept toward World War I, Mexican-Americans in the US border state had staged a short-lived revolt against new, non-Hispanic settlers who saw prominent landowners of Mexican descent as inferior. Texas' governor in the early 1910s had sent the Rangers to the border region, ostensibly to broker peace. But it wasn't to be.

"(B)y 1916, hundreds of untrained Rangers patrolled the state, often reigning with terror and intimidation," according to the Bullock Texas State History Museum . "They were assassins with a badge," said historian Trinidad Gonzales, who counts a relative among those murdered during the era.

During this time in South Texas, anyone who looked "Mexican" was racially profiled as a crime suspect, said Monica Muñoz Martinez, a Brown University assistant professor who wrote about the period in her book, " The Injustice Never Leaves You ."

"That meant that whether you were an American citizen or an ethnic Mexican ... you didn't have the protection or the presumption of innocence until proven guilty," she said. "When ethnic Mexicans had encounters with police, it was very common that people disappeared."

Those who vanished often turned up dead, their bodies left to rot. The custom was used to intimidate, to incite terror and to discourage families from seeking investigations or prosecution, Martinez said. It all fueled a culture of impunity.

The era's racist rhetoric is captured in the handwritten caption of this historical photo.

"It is estimated that hundreds, possibly thousands, of Mexican Americans and Mexicans were killed" during the years of La Matanza, reads a state marker now planted along Interstate 69 near San Benito, Texas.

Some 300 deaths happened in the Rio Grande Valley during the late summer and early fall of 1915 alone, estimated Gonzales, a history instructor at South Texas College. Among the slain were Bazán and Longoria.

When their empty-saddled horses arrived to Coody's great-grandmother's ranch house, her family knew something had gone horribly wrong. But they were too afraid to push the issue, Coody said. Her great-grandmother, Epigmenia Treviño de Bazán, never claimed the bodies.

"This was so painful for my family," Coody said.

In the humid South Texas heat, the remains of Bazán and Longoria festered. After two days, the stench of their decomposing corpses became unbearable, Warnock recalled

'They shot them off their horses'

Roland Warnock recalls the deaths of two Mexican-Americans, Jesus Bazán and Antonio Longoria, who were shot in the back and left to die on September 27, 1915. Source: Trans-Pecos Productions © All rights reserved

Roland Warnock

"We couldn't hardly sleep on the ranch because of the smell," he said in the documentary. "Human scent is the worst scent in the world."

Warnock buried the men's bodies on the morning of September 29, 1915, accounting for the date -- two days after their death -- etched into their headstones, one of which remains at the plot, while the other looks to have been replaced with a newer slab, Coody said.

More than 100 years later, Molis stood over those graves in the cemetery along the country highway. These men had starred in her family tragedy for as long as she could remember. But until now, she'd been separated by place and time from their violent demise.

Melba Coody stands at the graves of Bazán and Longoria in Texas' Rio Grande Valley.

"It's overwhelming," she said. "I didn't realize this is the spot they were killed."

"It happened so many years ago, but it still brings sadness and grief," her mother said. She walked toward the cemetery gate, lifted its metal latch and stepped toward the car.

A church that never hosted their funerals

Back in the driver's seat, Molis continued down the lane toward the church her once-affluent family owned and shared with its ranching neighbors.

Laying eyes on the one-room chapel, tears started to streak Coody's cheeks. The structure's roof had caved in. Its leaning steeple showed fissures. Molis put an arm around her mother, who suffers from diabetes. Did she need food or water, the daughter asked.

"I'm OK," Coody said, wiping her face.

Bazán and Longoria would have been honored with a Catholic funeral at this family church, Coody said.

If her great-grandmother had claimed Bazán's and Longoria's remains, Coody's family would have held a funeral at this church, she said. The entire community would have gathered to honor the dead in the Catholic tradition.

"They didn't even get to see the bodies," Coody said. "(Someone) just told them, 'This is where they were buried,' maybe a week later."

Bazán and Longoria didn't get caskets, Coody said. They weren't issued death certificates. No wake. No last rites. No death investigations. There was no prosecution. No jury trial. No justice.

Still, their loss doesn't live only in regional lore. Both men's names appear on a pair of key documents obtained by CNN: a record held in the US National Archives titled, "partial list of Mexicans killed" in the Rio Grande Valley in 1915; and one from Mexico's Genaro Estrada Historical Archives , "Partial list of Mexicans murdered by the Rangers." Their description as Mexicans reflects the era's bigoted vernacular, not a declaration of citizenship.

The names of Jesus Bazán and Antonio Longoria are listed in a document at the National Archives at College Park, Maryland.

Most people at the time were too afraid to speak out against the violence. But in 1919, Texas lawmaker J.T. Canales faced down death threats against himself and his family and led a joint state House and Senate investigation into the Texas Rangers. At the time, Canales, who represented the Brownsville area, was the only Texas state legislator of Mexican descent.

More than 1,600 pages of testimony from dozens of people, including officers, landowners and attorneys, make up the most complete set of evidence historians cite when referencing the extrajudicial killings of Mexican-Americans at this time in South Texas.

United States soldiers deployed to the US-Mexico border during The Massacre era pose for a photo.

The findings revealed a bitter culture among some of the state's lawmen. "Many of the men of the ranger force pride themselves in their reputation of being quick with their guns and desiring to have the reputation of bad men rather than faithful and efficient officers of the law," the legislature's joint investigative report found.

Texas state Rep. J.T. Canales

The probe also exposed crimes of the highest order. "We find that some of the commanding officers ... are responsible for the gross violation of both civil and criminal laws of this State," the report stated. Lawmakers cited offenses including extrajudicial killings, murders, confiscation of firearms without warrants and incarceration without due process.

One witness, E.A. Sterling, testified that then-Gov. James Ferguson had told him he'd "given Ransom" -- the Ranger captain linked to the killing of Bazán and Longoria -- "instructions to go down there and clean up that nest, that thing had been going on long enough, and to clean it up if he had to kill every damned man connected with it." Added Ferguson, according to Sterling, "I have the pardoning power and we will stand by those men, and I want that bunch -- that gang cleaned up." Ferguson later was impeached on matters unrelated to the Rangers.

Hundreds of pages detail the findings of a 1919 Texas state investigation into the Rangers' actions.

Texas Rangers and their attorneys gave testimony justifying excessive force and denial of due process, Martinez said. They called people of Mexican descent -- including US citizens -- inherently violent and disloyal to the United States.

"Today, we talk about MS-13 and gangs, but 100 years ago, people were talking about (Mexican) bandits and the need to police them violently," she said, referring to the criminal enterprise Trump has called "violent animals."

Mexican officials recorded the deaths of Bazán and Longoria.

As a result of the investigation, the Texas Rangers force was downsized from more than 1,300 personnel to fewer than 100, Martinez said, though some former Rangers went on to become sheriffs, prison guards and border patrol agents. And salaries were hiked in an effort to recruit "men of high moral character," according to experts and the report.

So many years later, Rangers still operate as a division of the state's Public Safety Department , handling public corruption investigations, tactical incident response and border security operations. The organization's century-old history of violence has no connection to the modern-day force, a department spokesman told the San Antonio Express-News in 2004.

"There's zero correlation," Tom Vinger told the newspaper.

The Ranger Division and representatives for Gov. Greg Abbott did not respond to CNN's requests for comment.

Their silence came as no surprise to Texas state Rep. Terry Canales, the great-nephew of J.T. Canales and a lawmaker representing the Rio Grande Valley.

"It's not something they're either proud of or that they want to acknowledge," Terry Canales said of the bloody chapter. "It's a way to try to either avoid it or pretend like it didn't happen."

A powerful plaque that links past and future

Down the road east of the church stands a metal marker surrounded by a white wooden fence. "Bazán and Longoria murders," reads its title, offering a painful but powerful testament to Coody's family story.

"It makes you feel chills," she said as she walked toward the plaque. "It feels like it just happened."

Relatives and historians pushed for official acknowledgement of the killings.

The sign stands in the heart of a place that remains a sort of ground zero of the modern immigration debate, where more than 1,000 migrants are apprehended daily by US Customs and Border Protection agents of the Rio Grande Valley Sector, the agency reported this month . "The majority of these apprehensions are people turning themselves in to the first Border Patrol Agent they encounter," it noted.

Nearly two dozen of Coody's relatives and friends gathered recently at the historical marker to share their grief over the deaths of Bazán and Longoria. Many could not ignore the story lines unfolding in their own time around questions of national identity, race and ethnicity.

Bazán's great-great-granddaughter, Carla Villarreal, cited today's political rhetoric to argue that the history is repeating itself. She recalled the 2015 speech that launched Trump's campaign for president, in which he referred to Mexican migrants as "rapists," as well as his use of the term "invasion" to describe the arrival of Central American migrants to the US' southern border.

Trump joked during a recent rally in Panama City Beach, Florida, about the treatment of migrants crossing the border, chuckling when a rally-goer suggested shooting them. "That's only in the Panhandle you can get away with that statement," the President said in early May.

"Everybody is a murderer, a thief, a rapist, a gang member," Villarreal told CNN of the modern perception some have of Hispanic immigrants. "That is not true. The rhetoric is terrible."

Trinidad Gonzales

Gonzales, the historian, argued that dehumanizing a population is a first step toward justifying its abuse. He doesn't believe today's immigration rhetoric will lead to the killings of Mexican-Americans, per se, he said, but warned that allowing dangerous commentary to continue unchecked will pave the way for their mistreatment.

Another relative, Irma Bazán Villarreal, said she doesn't think the massacre period is "going to be repeated because no one comes out and shoots them because they are coming across (the border)."

"Back then there was just no law and order," she told CNN.

But another descendant, Roberto Rodriguez, advised: "If you don't know history you're doomed to repeat it." He pointed to US troops getting dispatched to the Mexico border . "I think this type of policy normalizes the notion that the group is a threat, which can have the consequence of violence directed at that group," he said.

In Texas, officials haven't all learned from the dark history, state House member Canales said, noting the so-called "show me your papers" law that allows Texas law enforcement officers to ask about someone's immigration status during a lawful stop or arrest. The ACLU and others have criticized it , saying it corrodes trust in law enforcement.

"I tell people that history may not repeat itself," Canales said, "but it sure rhymes."

The gathered descendants agreed on one thing: the killings of Bazán and Longoria changed a family forever.

"Who knows where we would be now if this hadn't happened, if my grandfather would have lived, if he would have raised the children," wondered Hector Garcia, a relative of Bazán.

Descendants of Bazán and Longoria gather to reflect on how their relatives died and to discuss modern immigration.

Coody's great-grandmother became a single mother of 10 children overnight when her husband, Bazán, was killed. To make ends meet, she sold most of her property, though not before setting aside 107 acres for each of her children, Coody said.

Christine Molis

Together, the family lived off the land, planting vegetables and corn for tortillas. They bottled their own tomatoes and even had a recipe to make candy from beans. The siblings stayed on the ranch until the 1950s, she said, then spread out to towns across the Rio Grande Valley.

"To me, what happened that day changed our destiny as a family," Elizabeth Bazán Puente, 53, said of her great-grandfather's fate. "All of us here would have grown up so much closer."

"It's an injustice that never leaves you," Coody said.

Still, Coody wouldn't want to bury the past, both in case it could spur a more compassionate future and because it is part of her. "I think that my daughter, who is very involved, will keep the story going," she said.

"It's our family history," Molis agreed, "and it needs to be told and retold."