Environmental leader Berta Cáceres was in her modest house in La Esperanza, Honduras, with fellow activist and Mexican national Gustavo Castro Soto on March 2, 2016. Cáceres had purchased the home with award money from the Goldman Environmental Prize, which she won in 2015 for rallying her indigenous Lenca community against a proposed dam. It was the first house she had ever owned, and it was meant to provide sanctuary from the intensity and danger of her work. Shortly before midnight, gunmen kicked in the door and fired six shots into her bedroom, hitting Cáceres three times. Castro, who was also shot, rushed to her side, and cradled her as she died.

During her funeral procession a few days later, a crowd of thousands wound down the street with a mix of grief and defiance, chanting what would become a rallying cry, “¡Berta vive, la luche sigue!” or “Long live Berta, the struggle continues.” Cáceres’s four children vowed to channel their anguish into pursuing justice for their mother’s killers and carrying on her work. Daughter Bertha Zúñiga Cáceres has stepped up to fill the void, taking over leadership of the Civic Council of Popular and Indigenous Organizations of Honduras (COPINH), the organization her mother co-founded decades ago. It wasn’t long before she too was attacked, barely escaping the assailants.

Born to an activist mother, Cáceres’s expansive and radical worldview inspired grassroots mobilization, fostered intersectional solidarity, and resonated around the world. She denounced the forces that conspired to immiserate her people: Local elites and transnational business interests that ravage the land, the architecture of international rules and institutions that uphold those practices, and the security forces that inflict a lethal toll on transgressors. At the award ceremony for the Goldman Prize, Cáceres exhorted listeners to “shake our conscience free of the rapacious capitalism, racism, and patriarchy that will only assure our own self-destruction,” and called for the world to wake up to the environmental devastation that endangers the planet.

The assassination of Cáceres ignited a global groundswell of outrage. Now an independent investigation has confirmed that powerful interests are trying to suppress the truth of the sprawling murder plot. In the report, titled “Dam Violence: The Plan That Killed Berta Cáceres,” five international human-rights experts reveal evidence that state agents, high-ranking executives, and employees of the company whose dam she resisted had participated in planning, executing, and covering up her murder. The report slams the Honduran government’s poor job of investigating and prosecuting those involved.

Several of the experts were in Washington on November 2 to present their findings to the media and sound an alarm: If Honduran authorities don’t preserve evidence and pursue unexplored lines of inquiry soon, the case will be permanently stalled, enshrining impunity for the crime’s masterminds and emboldening the corrupted Honduran institutions that protect them. That outcome would further imperil other vulnerable human-rights defenders.

In the aftermath of the killing, the Honduran government spurned the family’s repeated demands for an independent and impartial investigation, so they and COPINH requested one elsewhere. The International Advisory Group of Experts (known by its Spanish acronym GAIPE) started work last November. The inquiry was a daunting task, since the government turned over only a fraction of the evidence it collected and to which the family is legally entitled. Authorities are withholding critical cell-phone information that could shed light on the upper reaches of plot. Still, the experts conducted on-site visits and interviews, reviewed reports from human-rights organizations and experts, and culled through 40,000 pages of digital information. The investigators found incriminating WhatsApp messages, such as communications in the days surrounding the killing between the named suspects and an executive from Desarrollos Energeticos SA, or DESA, the company building the dam.

“Despite the secrecy of the Public Prosecutor’s investigation, GAIPE has been able to establish the participation of executives, managers and employees of DESA, of private security personnel hired by the company, of state agents and parallel structures to State security in crimes committed before, during and after…the day of the assassination,” the experts concluded. “Those crimes remain unpunished.” This evidence of high-level orchestration by DESA has been available to authorities since May 2016, yet they’ve declined to take action, the report says.

DESA has denied the allegations, claiming that the government’s investigation is ongoing, the experts are biased, and the report was released weeks ahead of upcoming elections for political purposes.

As with anything in Honduras, the United States looms large in this case. Honduras has been a US “captive nation” for over a century, serving Washington’s military, geopolitical, and economic interests. It historically functioned as a conduit for transnational investment, such as American banana companies, and was later the staging ground for the US-supported contra death squads in Nicaragua in the 1980s. Today Honduras hosts the military base that anchors US military presence in the region and provides an important launching pad for anti-drug efforts.

Although the last century in Honduras has been largely marked by stark social exclusion and economic inequality, the climate for human rights deteriorated after the 2009 coup that overthrew democratically elected president Manuel Zelaya, who had instituted some populist reforms in a country long operating in service to its oligarchy. Then–Secretary of State Hillary Clinton declined to quickly characterize the ouster as a military coup to avoid triggering an automatic cutoff of US aid. The State Department then undermined negotiations aimed at ensuring Zelaya could return to finish his term, and sanctioned subsequent elections that were widely boycotted domestically and condemned by the international community. Since then, successive US-backed governments have put more Honduran territory up for sale to global businesses and investors, unleashing a wave of repression to protect those interests that has been particularly deadly for defenders of the environment.

Even for the US government, the killing of such a renowned figure was impossible to ignore. The day after her murder, then–US Ambassador James Nealon called “for a prompt and thorough investigation into this crime.” To bolster its ostensible commitment to building the rule of law, the United States has contributed expertise to the Honduran Technical Criminal Investigative Agency (ATIC), which is tasked with examining crimes with strong social impact, including the Cáceres case. During several visits to the embassy, both the current and former US ambassadors assured GAIPE that the investigation was being carried out in an exemplary way for Honduras.

That turns out to be an abysmally low standard. As Dana Frank, professor of history at the University of California, Santa Cruz, notes, “The ATIC is one of the US’s most-touted ‘special vetted units’—and yet it appears to be complicit in failing to pursue the case, perhaps deliberately.”

The international scrutiny did have some effect: Eight people have been arrested, including Sergio Orellana, who was DESA’s environment and social manager, and Douglas Bustillo, who was security director for the company until the summer of 2015, along with two men with ties to the military and contracted assassins. The government seemed to believe it could charge the crime’s material authors while insulating its real protagonists, a common strategy of repressive Latin American governments under pressure to solve killings that implicate powerful players. But those demanding justice for Cáceres are not satisfied with the government’s arrests of low-level operatives without holding to account those who originated and benefited from the plot, some of whom have now been identified by GAIPE, though not by name in the report.

The Gualcarque River is sacred to the Lenca, and they rely on it for food and irrigation. To them, defending the territorial integrity of ancestral land and the river’s free flow against top-down development is an existential and emblematic struggle. Unlike some large-scale projects being pushed forward in Honduras, the Agua Zarca hydroelectric dam is modest in size, just one of a number being pursued by DESA and international development banks that backed the company. It’s not the prospect for untold riches that is motivating the company’s intransigence: The project is symbolically important for DESA as well. The company and its allies wanted to send a clear message: Communities negatively affected by projects will pay a steep price for resisting them. And Cáceres, who had successfully led COPINH’s opposition to development projects for decades and emerged as a pivotal leader in the post-coup resistance, was a particularly valuable target.

According to GAIPE, the company devised a strategy “to control, neutralize and eliminate any opposition.” The panel emphasized that the murder was not an isolated incident but rather the culmination of systemic and structural efforts to fray the social fabric of the community, which included “smear campaigns, infiltrations, surveillance, threats, contract killing, sabotage of COPINH’s communication equipment; cooptation of justice officials and security forces, and strengthening of parallel structures to State security forces.” That strategy also included an aborted assassination attempt the month before Cáceres was killed. Harassment of activists continues to this day.

From the outset, the investigation was deeply flawed. Death threats were nothing new to Cáceres—she had reported 33 of these to Honduran authorities to no avail. Yet officials initially accused members of COPINH and alleged organizational infighting, before suggesting a former boyfriend was culpable. When those efforts to deflect blame became untenable, authorities shifted course and sought to cast the murder as the work of rogue employees. The ensuing criminal investigation seems to have been carried out with some combination of deliberate sabotage and appalling incompetence. In the hours after the killing, the crime scene was contaminated. Then a judge overseeing the case had her car stolen—and the case documents along with it. The file, which contained the identities of protected witnesses who understandably fear retribution, has never been recovered, nor was any perpetrator identified, signaling to others that they would come forward at their own peril.

The vast reach of the conspiracy and the depth of the efforts to cover it up are hardly surprising. Corruption is endemic to the Honduran government and its state institutions. A Carnegie Endowment for International Peace report characterized corruption as the country’s “operating system.” Under this model, the report argues, “Repression is carefully targeted for maximum psychological effect,” as with the targeting of Cáceres, whose international acclaim failed to protect her.

Despite this, the United States continues to ignore the structural rot and to buttress crooked strongmen. As Frank notes, “Signals indicate that John Kelly is running the US policy show in Honduras, along with Thomas Shannon, the architect of US support for the 2009 coup. Kelly has stated that he thinks President [Juan Orlando] Hernández is a ‘great guy, good friend’—despite the fact that Hernández is overthrowing the rule of law yet again by running a criminal campaign for reelection, explicitly forbidden by the Honduran constitution.”

Corruption has yielded catastrophic results. A 2015 scandal revealed that as much as $90 million was diverted from the already underfunded social-security institute into the election coffers of Hernández and his party, causing incalculable suffering.

Washington’s embrace of Central American authoritarians when they advance its own priorities is old habit. The region has largely escaped President Donald Trump’s attention, aside from his xenophobic and nativist rants against migrants fleeing violence and poverty. But his administration has been doubling down on its “America first” focus, promoting conditions friendly to foreign investment and stepping up militarization. The main funding for that initiative proposed to stem the flow of migrants, the Alliance for Prosperity Plan, imposes robust human-rights conditions on aid, adding a veneer of oversight. But so far the State Department has been loath to use the purse strings as anything other than an idle threat.

Since the coup, a small number of US lawmakers have expressed concern about the human-rights situation in Honduras, sending multiple letters to the State Department, but their admonitions and entreaties seem to spark little meaningful action. The State Department has continued to employ an opaque process to certify that Honduras complies with human-rights conditions despite clear evidence to the contrary, (including its own reports), such as its summary dismissal of credible evidence that Cáceres had been on a military hit list. Busy dismantling the department instead of building its influence, Secretary of State Rex Tillerson seems unlikely to critically review the human-rights certifications his more attentive predecessors weren’t even inclined to seriously undertake.

That raises the stakes for congressional action. Vermont Senator Patrick Leahy reacted quickly to the report: “It is shameful that despite intense domestic and international pressure, this horrific case has languished, while those responsible have sought to derail it…. There are hundreds of other Honduran social activists and journalists who have been similarly threatened and killed, whose cases have not even prompted investigations.”

Leahy, a long-time champion of US accountability for the impact of its security support abroad, vowed that there will be consequences if the Honduran government doesn’t muster the political will to unravel the entire conspiracy behind the murder of Cáceres and to impose justice on all the perpetrators. A number of other legislators have since echoed those sentiments.

But strong words are not enough. The Honduran government has failed to uproot impunity and corruption and to protect those fighting against suffering. Cáceres’s family has displayed great courage and tenacity in seeking justice for her death, at considerable risk to themselves. Washington should ensure their demands are vindicated. To compel decisive action, 67 members of Congress have co-sponsored the Berta Cáceres Human Rights in Honduras Act, which would require the US government to suspend security aid to Honduras until it adequately addresses certain human-rights benchmarks, including full justice for the murder of Cáceres. The bill also directs US representatives at multilateral development banks to vote no on all loans for Honduras. US civil society must accompany the brave and besieged dissidents in Honduras, and push our congressional representatives to support the Berta bill, even as they are occupied fighting escalating threats to human rights and core democratic principles at home. As Cáceres eloquently argued, the injustices we face, and our collective fates, are all interconnected.