Mexican priests have upholded the ancient traditon of exorcism and nowadays they're using it to battle against the country's longstanding war against drug cartels.

Father Ernesto Caro shared his story to a local news outlet, retelling the tale of the exorcism he performed on a Mexican drug cartel member.

The sinner was reportedly a Los Zetas cartel killer, the country's most heinous crime syndicate. The man, who was the source of the "most awful confession" Father Caro ever heard in his 22-year service, said his specialty was chopping his victims into pieces while they were still breathing.

"He said he smiled while he was doing it. He said he enjoyed it and that he was laughing," the Monterrey priest and exorcist told the local media outlet. "He told me terrible things."

According to the priest, it took almost four months of weekly visits to exorcise the killer of the demons possessing him.

The unnamed convict, who was arrested for murder and kidnapping, converted to the Roman Catholic Church in 2012 and started a new life free of violence, Father Caro confirmed. The priest added that the killer was granted an early prison release but his whereabouts remained unknown.

"God sends me these people," the Diocese of Monterrey priest explained.

Since 2006, cartel violence has steadily risen in Mexico, with more than 80,000 people murdered by warring drug gangs. The brutal savagery has spun out of control to an extent that in some towns in Mexico, dismembered, decapitated and disemboweled bodies are a normal sight.

Exorcism has gained popularity in recent years as a weapon against the rising violence of drug cartels, religious experts say. Though statistics remain undetermined, priests claim that the increased frequency is fueled by the heightened popularity of Santa Muerte (St. Death), the reported "saint" of narcotics syndicates. Santa Muerte has reportedly gathered around 10 million followers internationally with 20 percent of them residing in Mexico.

The Vatican has declared Santa Muerte's worshippers as a Satanic cult. Mexican priests blame the saint's cartel followers for the country's ever-increasing death toll due to acts of violence.

"People think they're demon-possessed, because they feel tormented … that evil spirits have engulfed them," Professor Andrew Chesnut of Virginia Commonwealth University said in an interview.

In recent years, "cartel members started praying to her for protection from death and protection from law enforcement. Since she's not a Catholic saint, if you want to ask her that your shipment of crystal meth makes it from Michoacan (a central Mexico drug stronghold) to New Mexico, you do that because she's not Catholic," said Chesnut, known for his book "Devoted to Death: Santa Muerte, the Skeleton Saint."