On May 11, 2012, in a joint U.S.-Honduras drug enforcement operation gone terribly awry, four Honduran civilians, including two women, a 14-year-old boy and a young man were killed as they traveled in a fishing boat along Honduras’s Patuca River. Three other passengers were seriously injured. U.S. government officials have minimized the Drug Enforcement Administration’s role in the attack, characterizing its involvement as merely supportive.

U.S. and Honduran officials have cast the victims as participants in drug-trafficking operations, and maintain that agents acted in self-defense. Human rights groups who conducted multiple witness interviews and reviewed forensic evidence, however, paint a starkly different picture of the events that day.

In the aftermath of the shootings, witnesses reported that English-speaking men dressed in U.S. military uniforms threatened local community members, contradicting the official U.S. position that its agents were only peripherally involved. Then a report by the Honduran National Commission for Human Rights (CONADEH) revealed that Honduran police agents who participated in the operation said they were following instructions from the DEA and reported only to its agents. Now, after much scrutiny from Congress and human rights groups, U.S. officials have acknowledged—after many initial statements to the contrary—that DEA agents led the May 11 operation because they “did not feel confident in the Hondurans’ abilities to take the lead,” according toThe New York Times. Despite the DEA agents’ central role, the U.S. government has downplayed looking into the incident—the DEA is supposedly conducting an internal probe, away from public scrutiny—and has instead promoted an investigation by Honduran authorities.

Yet, as the U.S. State Department itself has recognized, the Honduran judiciary has an appalling track record when it comes to investigating and prosecuting violent crimes, particularly when members of the country’s own security forces are involved. Furthermore, the U.S. government signaled a clear lack of trust through its recent decision to suspend radar support for Honduran drug-interdiction efforts after two planes were shot down in violation of prior agreements. Given the evidence of American responsibility for the May 11 incident, U.S. authorities should undertake a separate, independent inquiry.

The official Honduran investigation was flawed from its inception. Many eyewitnesses and survivors say Honduran officials made no attempt to interview them. Instead of acting quickly to preserve the integrity of forensic evidence, investigators did not perform autopsies on the victims until 43 days later, when the bodies were severely deteriorated and their evidentiary value compromised. The chain of custody for other evidence was sloppy, and some of it was lost.

Other critical evidence was completely overlooked. For example, the DEA possesses surveillance video of the episode, but has neither made it public nor turned it over to Honduran investigators. Honduran authorities have not questioned the U.S. agents involved or inspected the weapons they carried on May 11, though ballistics evidence could shed light on who fired the fatal shots.

The United States should be exceedingly careful about militarizing counter-narcotics efforts.

In sum, the investigation was deficient by any standard: its findings are contradicted by forensic evidence, the testimony of multiple eyewitnesses and survivors, and even the positions of Honduran officials themselves, according to a detailed report published by Center for Economic and Policy Research and Rights Action. Honduran human rights groups and CONADEH have also called for an independent U.S investigation.

The United States can and should carry out its own independent probe of the incident. The State Department Inspector General can initiate an investigation, given the use of State Department helicopters during the operation. In light of the central role played by the DEA, the Department of Justice Inspector General should also investigate to ensure that its operations complied with agency standards and with U.S., Honduran, and international law.

The United States has a moral obligation to assist the victims. Relatives of the deceased were already struggling to survive in grinding economic hardship before losing their critical support, while families of injured survivors face crushing medical expenses. Rather than maligning the victims, the U.S. government should provide financial support to their families, who suffered damages from a flawed operation involving its agents, helicopters, and weapons.

On a global level, as the U.S. expands its drug interdiction efforts to Africa and elsewhere, critics are expressing alarm about the impact of those policies on countries already rocked by instability and weak democratic institutions. Given the deadly toll the drug war has exacted in places like Honduras, BoliviaMexico, and Colombia, the United States should be exceedingly careful about the consequences of militarizing counter-narcotics efforts. It already stands accused of violating human rights in the War on Terror, from its drone strikes and Joint Special Operations Command death squads to its enhanced interrogation techniques and indefinite detentions. The abuses from the drug war in Central and South America have been widely reported amidst growing skepticism of its efficacy and recognition of its financial and human costs. Moreover, the United States has shifted funding—and personnel—freed up by the reduction of troops in Afghanistan and Iraq to the drug war in Central American and Africa with little public notice or debate. The Obama administration, in concert with the DEA and the State Department, must conduct a methodical and transparent re-examination of the current strategy.

The killings in Honduras occurred against the backdrop of escalating violence and lawlessness in that country since the 2009 coup, and growing criticism of the war on drugs. Because of the human rights implications of the militarization of the drug war, the United States must set a model for accountability by investigating and rectifying the collateral effects of the Honduran operation and its drug interdiction policies in general.