In reviewing several works on Mexico's drug wars for the New York Review of Books, Alma Guillermoprieto herself gives a rundown of the cartel culture in Mexico. 

The Murderers of Mexico

The murder rate in Mexico City is eight per 100,000, comparable to Wichita, Kansas, or Stockton, California. The overall murder rate in Mexico is fourteen per 100,000. But in Ciudad Juárez it is 189 per 100,000. And as in Tijuana, Reynosa, or Nuevo Laredo—other border cities also afflicted by runaway violence—all but a very small number of the Juárez victims are, in fact, involved in one way or another in the drug trade.

She refuses to call Mexico a failed state because they build schools and collect taxes, but paints a picture of a government, military and police force riddled with corruption based on the lucrative drug trade. She tries to identify what drives the cartels, because they are far more violent - savagely and creatively violent - than required by their business plan. One possibility is machismo, another is religion - but a perverse sort:

What we have in the place of collaboration is the shattering loneliness of Juárez. In the 1990s, when young women began to disappear from the poorest shantytowns in the city, and then turned up like so much waste matter, bruised, raped, mutilated, and dead, police officers laughed in the faces of the distraught parents who appealed to them for help. Reporting on the story, I stood one afternoon on a gray hill covered in gray dust above a gray squatter settlement and looked across the river at the faux-adobe office buildings of El Paso. Around me the tumbleweed jittered in the breeze, and plastic supermarket bags and odds and ends of clothing fluttered everywhere, as if all the trash in all of Mexico had beached itself at this spot. A few hundred yards downhill lived the sister of one of the disappeared girls, and for all the outreach by NGOs and solidarity groups concerned with the murders, she seemed as isolated and vulnerable as it was possible for a young woman to be.

Speculation has been never-ending about who was responsible for the murder of those girls—there were several dozen of them, tangled among the statistics for hundreds of other, more random female homicides. It was always clear that the police were somehow involved—the grotesque laughter at the police station, the switched clothing on a couple of bodies eventually returned by police to the bereaved families, the systematic destruction of evidence, all pointed in their direction. But it seemed unlikely that lowly police officers would have the political backing to engage on their own in sick serial murders and remain unpunished, even as a worldwide campaign mounted to protest the killings.

I remember asking back then if a likely culprit might not be the lord of Juárez, Amado Carrillo Fuentes, who was the most powerful trafficker of his day. Who else, in the course of doing regular business, could buy off enough politicians, police commanders, and justice officials to guarantee himself immunity under any circumstances? Conceivably, Carrillo Fuentes or his minions had developed a fascination with death that went beyond the strictly professional. Several of the girls had one breast sliced off, and in a shack in the desert some weird graffiti seemed also to have ritual meaning.

None of us reporters understood much then about the new religious cults mushrooming in the drug world—notably the Santa Muerte, or Holy Death, a Halloweenish figure identical to the hooded skeleton who makes frequent appearances in biker art. Her cult has spread well beyond the jailhouses where she is revered, and now that altars to the gloomy skeleton are everywhere in the country and we have heard of young migrant girls from Central America being killed and offered to the Santa Muerte by the particular branch of the drug mafia devoted to human trafficking, there is more reason to wonder if the current traffickers’ obsession with nauseating forms of murder did not start back then.

Likewise, Sinaloa traffickers form a cult around their bandit hero, Jesús Malverde, the narco-saint - sort of a Robin Hood figure to the rural poor in that area. I read about Narcocorrido music a long time ago. Although supposed to be the Mexican gangsta rap, it is actually accordion-based folk music often featuring a series of staccato sounds in imitation of gunfire. Narcocorrido goes back decades, but recently its prominent musicians have been murdered themselves.

Reading about the the cults and the killings, I can't help but think of Kurtz's cult in Heart of Darkness or the pig head idol in Lord of the Flies. I suppose the more one becomes a beast, the darker the beast one has to worship.