The F. B. I. is investigating the apparent attack on two border officers in the Texas desert, which killed one and came amid a rise in assaults on agents.
Along the vast rocky desert that stretches from Mexico into rural West Texas, Border Patrol agents like Rogelio Martinez frequently work alone, miles from civilization and from help.
Agent Martinez loved the work, said his father, Jose Martinez. He also knew the risks. The job’s two responsibilities were stopping illegal border crossings and halting drug trafficking.
Around 3 a.m. Sunday, Jose Martinez was awakened at home in El Paso with the phone call he had long dreaded.
Summoned to the University Medical Center of El Paso, where doctors were trying in vain to resuscitate his son, Mr. Martinez got a sense of what had happened in the desert about 100 miles away when he saw Rogelio’s bloodied head.
“It was difficult to look at,” he said.
Agent Martinez, 36, was killed, and a second agent who had apparently come to his aid was seriously injured, in what the federal authorities were treating on Monday as an attack. The F. B. I. was leading the investigation, and did not say Monday whether any arrests had been made.
Details were thin, but the episode in a remote stretch of Texas quickly made its way into the national conversation on immigration and border security. While Border Patrol fatalities are relatively rare, agents are not infrequently attacked on the job. And despite a dramatic drop in border crossings under the Trump administration, assaults against officers have risen, according to data maintained by the border agency: 720 in the recently-completed fiscal year, the highest number in at least five years.
Chris Cabrera, a spokesman for the National Border Patrol Council, the officers’ union, said that individual border agents often arrest dozens of people at a time without any help from colleagues. Most people surrender, but that is not always the case. A favorite tactic among border crossers is to hurl debris from the rugged terrain at officers, and Mr. Cabrera said that he had personally been on the receiving end of rocks thrown at him that were the size of grapefruits.
“If they hit you in the head, you’re going go to sleep,” he said.
Over the weekend, the agents had been patrolling along a remote section of the border near Interstate 10 in Culberson County, Tex., where drug and human trafficking are common.
Mr. Cabrera said that according to other officers who were on duty, Agent Martinez went to check out a Border Patrol ground sensor that had been activated. The sensors, concealed devices that remotely alert agents when triggered, can be set off by wild animals, dying batteries or even the wind. Agent Martinez confirmed over his radio that it had been set off by humans, Mr. Cabrera said.
Agent Martinez called for backup, and when his partner, whose name has not been released, arrived, the partner called out over the radio that Mr. Martinez was unconscious. The officer requested more support, Mr. Cabrera said.
Mr. Cabrera said that officers who arrived next found both men unconscious, and took them to the hospital. He said that the officer who survived the incident was still recovering and remembered very little of what happened. Most of what was known had come from officers who overheard the radio traffic, he said.
Given that the attack occurred in what is essentially ground zero in the national immigration debate, officials quickly seized on it, including President Trump, who campaigned on a promise to build a wall along the Mexican border but has yet to secure the funding for it.
“We will seek out and bring to justice those responsible,” he posted to Twitter on Sunday, “We will, and must, build the Wall!”
Senator Ted Cruz, the Texas Republican who is running for re-election in 2018, echoed the president’s sentiments in a statement. “This is a stark reminder of the ongoing threat that an unsecure border poses to the safety of our communities and those charged with defending them,” he said.
Beto O’Rourke, a Democratic congressman from El Paso who is running for Mr. Cruz’s Senate seat, published a blog post that avoided mention of the wall. Instead, Mr. O’Rourke, who opposes the barrier, expressed support for the work of Border Patrol agents like Agent Martinez, while acknowledging that the topic was contentious.
“They work under immense pressures, under a microscope, even under the dark of night,” he said, “We know firsthand how lucky we are to have their service and sacrifice.”
Even with the increase in violence against officers, experts who study the region said that fatal incidents were still far outside the norm. An official list posted online contains 38 deaths in the line of duty from 2003 to the present, not counting Agent Martinez. The Border Patrol has about 20,000 agents.
“It’s super rare for agents to be attacked and killed,” said Jeremy Slack, a migration expert and professor at the University of Texas at El Paso.
Professor Slack said violent incidents were often tied to the drug trade, rather than to people who were seeking to enter the United States to work or claim asylum.
Jose Martinez said that he had often worried about his son’s safety, and that he did not think officers should work alone in an area with so much criminal activity.
“What I don’t like is at night, there is only one person,” he said, speaking in Spanish. Referring to his son’s attackers, he said: “I think they put a trap.”
Agent Martinez, who had an 11-year-old son, turned to work in immigration enforcement after struggling to establish a career in graphic design, which he had studied.
“He was always a good son,” Mr. Martinez said. “He was happy. He loved sports.”
As is true with many border patrol agents in the Southwest, Agent Martinez’s family did not neatly fit into one camp or another in the national debate over immigration.
Mr. Martinez’s said that his son had been proud of his work to protect the country, but that at times, felt conflicted about having to arrest so many Latinos.
Mr. Martinez was born in Mexico and is now a United States citizen. He entered the country with temporary permission to work in construction.
Agent Martinez’s aunt, Olivia Barnes, had once lived in the United States illegally after overstaying a tourist visa.
