MEXICO CITY (Reuters) - Discrepancies plague the official account of a deadly assault last year in which Mexican police allegedly executed 22 suspected gang members, burned bodies, manipulated the crime scene and tortured survivors, newly-revealed details show.

Police tape is seen at the entrance of a ranch where a firefight of armed civilians with federal forces took place on May 22, 2015, at a ranch in Tanhuato, state of Michoacan, Mexico, June 28, 2016. REUTERS/Frank Jack Daniel

In May 2015, a woman walked into a police station in the western Mexican city of Guadalajara and told investigators a group of about 50 men had broken into a local ranch she administered and said they wanted to buy the property.

It was not the first time the men, suspected members of the fearsome Jalisco New Generation (JNG) cartel, had visited the “Rancho Del Sol,” just outside the town of Tanhuato: According to one of the ranch’s tenants, they first appeared in 2014, demanding access to tap oil pipes that ran through the property.

The woman, whose husband owned the ranch until he disappeared after being kidnapped in 2012, asked security forces to go to the property and flush out the intruders.

Around 6.30 a.m. the following morning, dozens of federal police officers backed up by a Black Hawk helicopter raided the farmhouse, killing a total of 42 suspected gangsters, of which 22 were executed, according to a scathing report published by Mexico’s National Human Rights Commission (CNDH) on Thursday.

The incident described by the CNDH represents one of the most egregious rights violations by security forces in Mexico’s dark decade of drug violence, a menacing mix of murder, cover-ups and ineptitude.

Only one policeman died in the fight, in which police apparently attacked the cartel as they slept. The one-sided death toll was one of the highest since President Enrique Pena Nieto took office in 2012 and pledged to end years of violence.

POLICE MALFEASANCE

Renato Sales, Mexico’s national security commissioner, rejected the charge of executions, saying police responded with legitimate force.

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But the 696-page report presents a grim laundry list of apparent malfeasance by the police, who were smarting from a series of painful JNG cartel attacks in the weeks leading up to the May 22 incident.

Images in the report show charred cadavers. In others, bodies lie soaked in pools of blood and mud, with spotless assault rifles laid suspiciously beside them.

Various witnesses, including the wives of victims, told investigators they heard police officers bragging about how they had caught the men unawares.

“It was the easiest job we’ve ever done. We hit them like little birds, asleep in their nests,” one police officer was said to have boasted.

The pregnant wife of one of the victims said that when she went to identify the body of her husband, whose toes had been cut off and his testicles burned, the police made fun of her.

“That is the product of a delinquent,” she said they told her, pointing to her belly.

TORTURED DETAINEES

The CNDH interviewed the three men who were arrested in jail, where they recounted how police beat them and threatened to shoot them. One of them said police made him fire a gun, while another said he was told to sign papers he was not allowed to read.

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

Nonetheless, the federal police was not the only institution singled out for blame. For example, in three separate cases, the Michoacan state prosecutor’s forensic (PGJEM) team was found to have written up two different autopsies for the same person.

“The experts and medical forensic officers of the PGJEM implicated were involved in acts and omissions that affected the legality, honor, transparency, loyalty, impartiality and efficiency (of the investigation),” the report said.