The authorities then sought a search warrant to question the four individuals about their citizenship, which ultimately led to their arrests for immigration violations. On Friday, the conservative organization Judicial Watch posted a report sourced to anonymous “outraged Border Patrol officials” who complained that the agents’ inability to immediately enter the property resulted in a waste of resources and showed that the Trump administration wasn’t living up to its hard-line immigration enforcement pledges. Regarding the surveillance used in the case, the sources told Judicial Watch that a Border Patrol “Buckeye camera operated out of a mobile truck recorded the illegal crossers entering through Nogales.”

CBP quickly put out a statement following the arrests. “U.S. Border Patrol agents using surveillance technology Wednesday detected four suspected illegal aliens wearing camouflage and walking north on a known smuggling route,” the statement read. “Other agents then tracked the group to the No Más Muertes camp near Arivaca but did not find foot sign of the individuals leaving the camp.” The statement went on to say that members of the Tucson sector Border Patrol reached out to the humanitarian group “to continue a positive working relationship and resolve the situation amicably. The talks, however, were unsuccessful.”

As the property was surrounded, both sides were in regular communication, according to the accounts of both No More Deaths and U.S. officials. The aid group’s doctor made the case that the four men at the camp required extended medical attention as the government sought to obtain a warrant to search the property. On Thursday afternoon, the border guards got their warrant. “They came in with a military-style operation,” Gaffney said. Dozens of agents, multiple vehicles, and a helicopter descended on the camp, along with a government film crew to document the arrests. The official Twitter account of U.S. Customs and Border Protection’s Arizona branch live-tweeted the operation with photos. “We were immediately told that they were there to apprehend the noncitizens, and they actually used the term ‘bodies’ to describe those patients,” Gaffney said. “They said, ‘We’re not here to arrest any citizens, we’re just here to take the bodies’ — which in the context of the kind of death and suffering and the routine recovery of bodies of those who die in the crossing is pretty striking language.”

Stopped at the perimeter of the No More Deaths camp, Border Patrol agents took up locations around the property, Gaffney said. “From Tuesday afternoon to yesterday, our lawyers and medical team was in touch with Border Patrol being clear that, as we have for the last 13 years, our camp is a medical facility where people are able to receive care [and] that the patients that were there were in need of continuing medical care,” Gaffney said. From Tuesday on, Gaffney said, Border Patrol agents were “surveilling us constantly with anywhere from five to 10 trucks posted at different high points around the camp.” All vehicles leaving the property were inspected for undocumented passengers, Gaffney said, contributing to a sense of a “lock-down siege where anyone else who might be in distress and needing help would be completely unable to enter, and obviously interfering with our ability to give good care to those people who were there.”

Gaffney and other volunteers said the four men, whom U.S. Customs and Border Protection later identified as Mexican nationals, arrived seeking medical attention. Since its founding 13 years ago, No More Deaths has been best known for providing medical care to migrants making the perilous trek across the desert, and through the establishment of its camp near Arivaca in 2005. The arrested men ranged in age from 19 to 40, Gaffney said, and were suffering from heat-related illnesses, injuries, and exposure to the elements — ailments that No More Deaths volunteers, under the supervision of an on-site doctor, are accustomed to treating. “They all presented at the camp after having walked for several days through extreme heat,” Gaffney said. Temperatures in the area exceeded 100 degrees last week, and June is considered one of the deadliest months for migrants attempting to make their way across the desert.

The ordeal began at approximately 4:30 Tuesday afternoon, according to the aid group, when Border Patrol agents showed up at the property claiming to be in search of four men suspected of crossing the border illegally. The presence of the agents prompted No More Deaths to inform a network of volunteers about the situation. Catherine Gaffney, a longtime volunteer with the organization, was among those who received the alert and made her way to the camp. Speaking to The Intercept Friday, Gaffney, along with other No More Deaths volunteers, said what transpired this week suggests a chilling shift in Border Patrol tactics under the Trump administration.

A three-day showdown in Arizona’s Sonoran Desert between Border Patrol agents and a humanitarian group, which culminated in a raid and the arrests of four undocumented immigrants, has aid workers raising questions about government surveillance and operational practices. The arrests took place Thursday evening at a camp run by the group No More Deaths, also known as No Más Muertes, which is located on private property near the unincorporated community of Arivaca, roughly 11 miles north of the U.S.-Mexico border. The humanitarian group said approximately 30 well-armed Border Patrol agents descended upon the location looking for “bodies” in a coordinated and alarmingly militarized operation, leaving with the four men in tow.

Throughout the week, Margo Cowan, an attorney for No More Deaths, was responsible for communications with the government. Cowan said the acting chief of the Border Patrol’s Tucson sector made clear to her that the four men were first placed under surveillance near the border — on foot, the trek to the camp can cover anywhere from 16 to 18 miles, she said. “They concede that they picked them up on various electronic devices about 15 miles south of our camp,” Cowan told The Intercept. Cowan claimed Border Patrol officials told her arresting the men before they reached the No More Deaths’ camp would have been unfeasible. “I don’t buy that,” Cowan said. “I think that this was a setup. I think that they pick them up probably within minutes of entry to the United States and then they track them and they decide to surround the camp once they see that they go into the camp.”

Cowan said No More Deaths had a similar experience with border authorities a month ago — CBP referenced such an incident in its initial statement on Thursday’s arrests. In that case, Border Patrol had shown up at the encampment looking for migrants they claimed to be tracking. But a showdown was averted when the eight individuals voluntarily left the compound and were arrested. “We haven’t had any trouble for years and years. I felt like that was an anomaly,” Cowan said of the incident last month. “I felt like they did pick up the guys on the video and they tracked them into the camp and the fellows decided to walk out. But, for me, it happens time number two — it’s a pattern.”

“What that says to me is they have sensors on known routes. And, when somebody gets on those routes, they essentially track them from entry to coming into the camp. And then they call me and they say, ‘We tracked somebody into the camp, will they come out?’” Cowan explained. “For me, that is rendering the camp unable to provide humanitarian assistance because people are tracked in and then expected to come out.”

The government’s claims in the No More Deaths arrests initially contained inconsistencies. The CBP statement issued after Thursday’s arrests, for example, described the four individuals being detected on Wednesday. However, according to No More Deaths, the men who were arrested had already been at the camp a full day by that point, reaching the property shortly before the agents arrived. Volunteers at the camp have expressed particular concern at the way Border Patrol surveillance was deployed in the case, in part because it appears to imply close monitoring of the humanitarian organization’s operations.

The search warrant used in the case, a redacted portion of which was reviewed by The Intercept, described authorities looking for four individuals who were photographed “by a sensor” at 4:25 on Tuesday, minutes before No More Deaths claimed the men arrived at their camp. If this timeline is accurate, Gaffney and others said, it raises questions as to whether the Border Patrol is effectively keeping an eye on the front door of their aid station. That would be a significant break from past practices and constitute a major threat to lifesaving operations in the region, the group said.

According to No More Deaths, Border Patrol agents in the Tucson sector have for years upheld, through a verbal agreement, a set of principles modeled after Red Cross guidelines on the treatment of humanitarian aid organizations in dealing with the groups that provide treatment to individuals passing through the Arizona desert. One of the passages in the set of principles, shared with The Intercept, says, “Medical treatment provided by humanitarian aid agencies should be recognized and respected by government agents and should be protected from surveillance and interference.” Until recently, Border Patrol’s Tucson branch appears to have adhered to the outlined principles.

The Border Patrol office in Tucson did not respond to multiple questions and requests for comment regarding the surveillance used in Thursday’s arrests and the agency’s purported agreements with the humanitarian aid organization. On Friday night, CBP issued an updated statement on the case, amending the reported use of surveillance from Wednesday to Tuesday, and reporting that one of the four men arrested was previously arrested for drug-trafficking charges and spent five years in a Mexican prison. No further details were provided on the other three men taken into custody, aside from reporting that the group had been “taken to a local area hospital as a precautionary measure” and were said to be in “good health.”

In the same way that Doctors Without Borders provides humanitarian assistance to individuals in war zones regardless of their affiliations in the conflict, No More Deaths prides itself on offering to aid to those who, for whatever circumstances, end up in the Arizona desert in need of help. For the organization’s volunteers, it is the pattern of events this week and the implications for their future work that they find most distressing. “This the second time in a matter of weeks that they’ve attempted to penetrate the camp, that they’ve set this situation up,” Cowan, the attorney, said. “Prior to that, there weren’t these kinds of incursions and there wasn’t this kind of surveillance.”

Kate Morgan, abuse documentation and advocacy coordinator for No More Deaths, told The Intercept, “What is really different about this case is the warrant and the technologies, the military technologies, that [Border Patrol] used to obtain the warrant.” That tack, she argued, is “something new and I think is worth pointing to as signaling change in the way that Border Patrol is operating under the Trump administration.”

“What happened was not a routine apprehension,” Morgan went on to say. “It was a trap laid for people who needed medical attention and sought it from us. And we consider this an attack not just on our ability to give aid but a direct attack on the lives and well-being of people who are crossing the desert.” Gaffney, the longtime volunteer who was present for Thursday’s arrests, added that No More Deaths has always been a “transparent, above ground project,” and maintained open communications with Border Patrol since its founding. “We’ve always been clear that we have a humanitarian aid mission and we’ve been recognized by the Red Cross as a medical facility. We’ve never hidden that that’s what we’re doing there. We’ve always asserted our right to do it,” she said. “Nothing has changed in the way we’re operating. Nothing has changed in the law. What’s changed is their decision to attack us.”