Mexican Federal Police “arbitrarily executed” dozens of suspected cartel members on a ranch last year, according to a human rights monitor, firing thousands of rounds from a helicopter gunship. Many of the men were unarmed or fleeing, so federales spent four hours staging the scene to falsely incriminate many of the deceased, the Mexican National Human Rights Commission found.

Known by its Spanish acronym, CNDH, the commission published its report on the massacre last week.

Forty-three people were killed in the raid on Rancho del Sol, a private farm and winery a quarter-mile in size in the Pacific coast state of Michoacán on May 22, 2015. All but one of the deceased, a law enforcement officer, were supposed cartel members, although this is refuted by relatives of the deceased. Whoever they were, they never stood a chance.

Many of the dead were shot from above by a helicopter gunship, which the chief of Policia Federal, the Mexican Federal Police known colloquially as federales, claimed was “decisive” in supposed confrontation.

Police say they were headed to Rancho del Sol in response to a complaint from the owner, who said a cartel had forcibly occupied her property on the southern edge of the town of Tanhuato. En route they encountered suspicious men who fired upon them then fled, they said. Federales pursued the gunmen to ranch, they say, where other cartel members joined the fight.

Jose Ignacio Cuevas Perez, mayor of the nearby town of Tanhuato, says the ranch had long been dormant, up until about a year and a half ago, when he noticed renewed activity and the beginning of an alfalfa crop. He confirmed that the owner, who lives out of town, filed a complaint, according to Radio Formula. Residents of Tanhauto and the adjacent village of Ecuandureo, the village immediately adjacent, said some of them had been hired to work on the property, and that a few days prior, on May 18, armed men had appeared at the ranch. They instructed ranch employees to continue their work as usual.

A resident of Ecuandureo who spoke to The Daily Beast via Skype, and who wishes to remain anonymous, was one of dozens who witnessed the assault from afar or heard the roar of gunfire.

He told The Daily Beast, with the help of a translator, that it made little sense to him that Federal authorities responded in such force—he described a “shitload of police”—or at all in fact, to a complaint of intimidation by a cartel.

“We make these complaints all the time here and almost always there is nothing done,” he said.

The recent successful attacks by the Jalisco cartel on government forces have embarrassed police, the man said.

“This was a message, a warning to the gang for trying to be the government’s rival. This is like leaving a severed head on the doorstep.”

Violence has spilled into Michoacán state from neighboring Jalisco, which has been gripped in an intensifying turf war between the insurgent New Generation cartel (Cartel de Jalisco Nuevo Generacion, CJNG) and Joaquín “El Chapo” Guzmán’s Sinaloa cartel from which CJNG splintered about three years ago. The CJNG is suspected in the 2014 murder of Tanhuato mayor Gustavo Garibay García, who had survived a 2012 attempt on his life. The assassination of Garcia was the tenth murder of a mayor in the state since 2009.

The U.S. Drug Enforcement Administration and Treasury Department have been working with Mexican counterparts in Jalisco to target CJNG’s supply and laundering operations.

Many outside of Mexico had their first introduction to the upstart cartel after CJNG gunmen abducted Guzmán’s son Alfredo in Puerto Vallarta on Aug. 15. The brothers are now free, the Guzman family confirmed last Sunday. Their release was negotiated by Ismael “El Mayo” Garcia, who acts as a kind of consigliere for the Sinaloa, reported the editor of the Mexican weekly Riodoce, a tabloid that focuses on crimen organizado and the lifestyles of the outlaw class.

The raid on Rancho del Sol may well have been an act of retribution. The CJNG have been in a tit-for-tat war with Mexican counter-narcotics forces like the federales. The cartel downed a Cougar helicopter on May 1, 2015 , and 11 days later the gang ambushed a police convoy and killed 14 officers. Mexican Marines killed six cartel members who fired a rocket at their Black Hawk helicopter in July 2015. The Mexican government has deployed extra command resources to the state including “at least two more Black Hawks,” according to the Interior Ministry.

Jalisco was the first Mexican state to acquire its own Black Hawk assault chopper in 2011. The Sikorsky gunships flown by Mexican police are all equipped with 7.62mm rotary cannons that fire 3,000 rounds per minute. (The choppers can optionally be outfitted with dual .50 caliber machine guns and two rocket launchers.) Mexico obtains the assault choppers through the Pentagon. The U.S. Department of Defense has given away and sold at a discount dozens of Black Hawks to Mexico through its Defense Security Cooperation Agency.

Federales recovered 42 guns from the ranch which they sent to the United States Bureau of Alcohol, Tobacco, Firearms and Explosives for tracing. The ATF determined that some of the guns are linked to the controversial “Fast and Furious” operation.

Fast and Furious was a gun-tracing operation started in 2009 at the ATF’s Phoenix office under Project Gunrunner, which allowed suspected gunrunners to “walk” with marked firearms on the theory that this would lead investigators to higher-ranking gunrunners. The bureau came under harsh criticism when the program came to light and it was learned that weapons had been trafficked to some of Mexico’s most violent criminal organizations, such as the Los Zetas cartel.

The authorities claimed the Black Hawk at Rancho del Sol had been used to “contain” combatants only, and had not directly fired upon them, AFP reported in July 2015. They denied reports that characterized the operation as a massacre.

“There was not one single execution, I can say that categorically,” Enrique Galindo, head of Mexico’s federal police, told local media in May 2015. Authorities had waited 10 hours after the carnage ended to make any statement at all.

Locals and relatives of many of the deceased questioned the Policias Federal version of events from the outset; some say their loved ones were killed performing part-time labor at the ranch.

The AP sought access to the autopsy reports, but were denied on the grounds that the records would remain “state secrets” for five years.

Cell phone footage shot in the immediate aftermath shows a thick pillar of black smoke rising above the ranch. Authorities claimed the smoke was produced by their “clean up” efforts, burning rubbish. But the scene within the ranch betrayed that claim as obviously false to almost any observer. After the thunder of lead was over, Rancho del Sol looked like the scene of a military airstrike, not a police raid.

The corpses that littered the grounds, ranch house and outbuildings told independent investigators a much different story than Federales provided, a wholesale slaughter in which two detained men were tortured.

CNDH’s investigation was exhaustive and far-reaching. The organization worked with more than one hundred experts in criminology, forensics, and other fields to collect and review a huge body of written, photographic, and physical evidence, and interviews were conducted with many government officials, relatives of victims, detainees, and other witnesses.

A federales force of 41 men, first asking locals for a back way into compound, quietly entered the ranch between 6:20 and 7:30 on the morning of May 22. They requested and received an additional 54 officers as well as the Black Hawk helicopter sometime later.

Their assault on the ranch lasted for three hours and obliterated most of the property. Fires were seen burning several hours after the gunfire stopped.

CNDH investigators divided the carnage into three zones in order to keep track of the corpses. Zone A was the smaller of two fields on the 170-acre ranch. Two bodies were found here—the men were shot from behind while fleeing, CNDH found. Zone B was the larger field, parallel to Zone A and as long but twice as wide, and contained 16 corpses. There were 24 dead in Zone C, the ranch house, pool, and outbuildings. The residence was large, filled with pastel porticos. Blood had pooled (warning: graphic) in the grout and over the tile on a columned-lined, cadaver-strewn patio, where every piece of furniture was overturned or destroyed.

CNDH determined that police had staged the scene to make it appear that more than a dozen persons, who had in fact been unarmed, were carrying machine guns, and in one case a rocket launcher.

The detailed inventory of deaths begins by noting that a half-dozen men were found barefoot and half-naked, others partially disrobed, and one man was discovered face-down in only a pair of briefs.

A man who died inside the ranch house, which was set ablaze by a helicopter barrage, had succumbed to blood loss from gunshot wounds, but soot in his trachea indicated he’d been alive to burn. The helicopter also fired 4,000 rounds into the wine cellar, igniting a fire that killed a male occupant.

At least five men were killed by direct fire from above, most likely with the 7.62mm cannon. Thirteen victims were shot from behind, 13 were unarmed. Several had bruises and other impact injuries, at least one man was contused consistent with having been struck by a moving vehicle.

CNDH determined that the bodies of seven people were moved from the locations they were killed, and a total of 16 bodies were deliberately positioned beside firearms. In some cases corpses were stripped of firearms they had been carrying and replaced with others of a different caliber.

It took months to identify 41 of the victims, and the commission reported that it had been unable to determine the manner or cause of death for 15 bodies. One body was burned too severely for any identification.

One man, whose body was identified by his pregnant widow, was found with his toes cut off and his testicles burned.

Three men somehow survived to be detained by police, only to be subjected to torture and forced to help taint evidence, they told CNDH. One detainee said he had been made to fire a gun into the air, and another said he had been forced to sign a document which he had not been allowed to read. All three said they were made to watch the executions of other men on the ranch.

“One officer ordered [the police] not to kill any more detainees, because he had already reported there were survivors,” one of the men recalled.

The commission has also investigated an incident that occurred one month later in Tlatlaya in the state of Mexico in which 22 were killed, half of them execution-style, and police had altered the scene to stage it as a two-way fight. Records obtained by the press indicate commanders gave orders to the police to shoot-to-kill (officers were told to “take down” cartel cells in the dark of night, using a slang form usually meant as “kill”).

“Since Tlatlaya, we believe our government is capable of anything,” said the man from Ecuandureo.

Senator Alejandro Encinas Rodriguez of the left-wing Party of the Democratic Revolution said during a Senate session that whether or not the dead were cartel members was irrelevant, because “if you begin with them, because they may be criminals, then tomorrow what? Maybe it’s criminals today but tomorrow it could be anyone.”

National Security Commissioner Renato Sales maintains that police “responded to an attack by members of the [CJNG], using proportionate and reasonable force against a hostile enemy. There were no arbitrary executions, as CNDH has claimed.” Sales also stressed that officers involved are entitled to the presumption of innocence. “They also have rights; they are people too,” said Sales.

More than 10,000 people have been murdered in Mexico in the first six months of 2016, according to statistics recently reported by the National Public Security System, and 1,229 of those were in Michoacán.