Mexico’s President Enrique Pena Nieto has sacked the head of federal police after a recent report revealed that officers serving under him had arbitrary executed nearly two dozen civilians in a drug raid last year.

Interior Minister Miguel Angel Osorio Chong said in a press conference that Enrique Galindo was fired to ensure a fast and transparent investigation into last year’s massacre.

Earlier this month, the independent National Human Rights Commission said Mexican police killed 22 civilians in “arbitrary executions” during a raid against the Jalisco Nueva Generacion drug cartel in the western state of Michoacan on May 22, 2015.

In the 2015 fatal raid, a total of 43 people were killed, including one policeman and numerous suspected criminals, but 22 of them were deemed arbitrary executions by police, according the human rights body.

The commission also accused the police of moving the bodies of those killed in the raid and placing guns next to them in an attempt to cover up the crime.

It also noted that a police helicopter fired 4,000 rounds into the farm where the suspects were hiding.

Renato Sales, the chairman of Mexico’s National Security Committee, has rejected the characterization of arbitrary executions and defended the actions of police, saying they returned fire in self-defense.

The incident is considered as one of the bloodiest battles in the Mexican government’s decade-long campaign against powerful drug gangs across the Latin American state.

Official figures show that more than 35,000 people are currently missing in the country due to drug-related violence, which has also claimed thousands of lives over the past few years.

Police corruption, drug cartels and organized crime are the greatest challenges facing Mexico.