Mike Wilson chuckles in the passenger seat as the car crawls in and out of cement craters at 5 mph on a road that looks like it’s been hit by a meteor shower. David Garcia is attempting to make a phone call in the backseat. The two middle-aged men, with silver ponytails hanging down their backs, are both members of the Tohono O’odham tribe. Yet they are, as Garcia says, “persona non grata on our own tribal land.”

Wilson, an ex-Presbyterian minister who says he was kicked out by his own congregants for leaving water for migrants, and Garcia, a former tribal council member, are on a mission to expose human rights violations by the U.S. Border Patrol on the Nation. They’ve been working with the ACLU—which has deemed the Tohono O’odham Nation “ground zero” for Border Patrol abuses against U.S. citizens—driving around the reservation, trying to rally enough tribal members to share their horror stories to build a class-action lawsuit. Wilson and Garcia say most tribal members have had altercations with Border Patrol agents. But on the Nation, these are the kinds of stories only whispered behind closed doors. So the two men have become pseudo-renegade detectives, following leads and asking the kinds of questions that, they say, have earned them the ire of the tribal people and government.

It was one of Garcia’s connections that brought him and Wilson to a tribal member who had been shot by a Border Patrol agent on the Nation in March.

When the duo arrived at Amon Chavez’s house they were greeted by a pit bull. They stayed in the car as the young man spoke to them from his driveway. He told them he’d been driving around with his cousin and a friend at the time of the shooting. He and the friend, who was also shot, were taken to the hospital and when Amon woke up, the door to his room was guarded by a Border Patrol agent. When he was released from the hospital his cousin, the driver, was arrested.

According to an FBI press release, the only news report on the incident, one night in March an on-duty Border Patrol agent “opened fire...after a U.S. citizen tried to ram him with a truck.”

Two tribal members were shot and hospitalized and the agent who shot them was put on administrative leave. The Tohono O’odham Police Department was investigating the incident along with the FBI, who would likely pursue charges against Amon’s cousin, the driver, for assault on a federal officer. Any more information about who these men were, why the Border Patrol agent decided to open fire on them, and why the person who got shot would likely be hit with federal assault charges while the shooter received paid administrative leave, was nonexistent.

I’d soon learn that the mystery of the shooting of Amon Chavez and his cousin was emblematic of the struggle between the Border Patrol and the Tohono O’odham people. While many on the Nation view the Border Patrol as an occupying army, there is an unspoken, inherent fear of criticizing such a powerful agency of the federal government.

“It’s this whole culture of violence on the southwest border,” Wilson says. “The Border Patrol acts with impunity and immunity.”