Another week, another decapitation. Last week's victim was a 42-year-old woman, a grisly statistic in a catalogue of slaughter that totals hundreds, perhaps thousands of victims, beheaded by executioners wielding knives, machetes, even chain saws. But this heart of darkness cannot be traced to Islamic State [Isis] or other Islamist killers hunted by the US and its allies.
Instead, Aide Nava was murdered by a drug gang in the Mexican state of Guerrero. She hoped to become mayor of Ahuacuotzingo, a regional town, in the June elections. Her husband, a former mayor, was killed last year. Their son was kidnapped for ransom. His whereabouts is unknown.
Nava's headless body was covered with a "narcomantra" - a sheet bearing a note written in red capitals - from Los Rojos, one of the drug cartels locked into a savage turf war for regional domination. "This is what will happen to all the - politicians who don't want to sign up - turncoats. Yours sincerely, Puro Rojo ZNS." The message was clear: no state control here.
The left-wing mayoral candidate was a victim in a war that has claimed at least 100,000 lives since 2006. The dead are sometimes displayed in grotesque public tableaux. In Guerrero the murder rate is 42.7 per 100,000, compared to the OECD average of 4.1. Decapitation is almost commonplace in Mexico; last year at least 341 people died that way. Last year Jesus Castillo, a hit man for the Barrio Azteca cartel, told a US court in El Paso that he stopped counting his victims - many decapitated - after they reached 800. His bosses demanded a daily quota of eight to spread terror.
If the carnage in Iraq can be attributed, in part, to America's thirst for oil, Mexico's massacres are collateral damage to an insatiable US appetite for narcotics. The US Justice Department estimates drug trafficking is a US$30 billion ($40.4 billion) a year industry, or 3 to 4 per cent of Mexico's US$1.2 trillion GNP.
Mexico's agony - Hillary Clinton likened it to an insurgency - has fuelled growing anger at President Enrique Pena Nieto's conservative Institutional Revolutionary Party [PRI] Administration. Elected in 2012, he vowed to restore order, arresting several narcos, including the Sinaloa Cartel's Joaquin "El Chapo" Guzman. But the underlying problems - rampant corruption, poverty, violence and weak governance - remain entrenched.
Public anger exploded in September, when 43 student teachers vanished in Iguala, also in Guerrero. According to Mexico's Attorney-General, they were kidnapped by police, then murdered, mutilated and burned by gang members. So far just one has been identified from charred remains. Their deaths were allegedly ordered by Iguala's mayor, arrested with his wife. The students joined 23,000 people "disappeared" during the drug wars.
Ironically, the Iguala massacre, like similar outrages, is an unintended consequence of Mexico's war with the cartels. Back in the 1980s the major cartels operated with impunity, protected by Government officials, says David Shirk, director of the Justice in Mexico Project at UC San Diego. By smashing the status quo Mexico has unleashed a more anarchic, savage climate where smaller gangs proliferate, with dire consequences for local authorities and officials. The massacre is a sign of the times, "a blending of local political agendas and criminal savagery".
Street and social media protests demanding Pena Nieto's resignation have intensified a clampdown on dissent. Yet, Shirk cautions against speculation the Iguala massacre may spark political change. "Every time there's another massacre or horrible killing, people ask, 'Has Mexico turned the corner or is this the last straw?' And there's always another straw, there's always another corner."
One atrocity is superseded by the next. In a grisly coda to the Iguala massacre Shirk says a 44th student was also abducted that night. "They found his body. His face was severed off."
Writing on Al Jazeera, Musa al-Gharbi, a senior fellow with the Southwest Initiative for the Study of Middle East Conflicts, says Mexico's cartels are more lethal than Isis. Yet, even Isis claims a higher purpose: the creation of an Islamic caliphate. The cartel blood count is strictly business.
It is a sharp contrast with a century of Latin American left-wing conflict, most recently Mexico's Zapatista movement. "All these young men who've died in the past decade or two, if they had come of age 40 years ago they would be picking up a gun for a cause," muses Shirk. "Today they pick up a gun to make a buck. It says something about the current era in Latin America." It is an era defined by neoliberalism, notably the 1994 free trade Nafta deal between the US and Mexico that impoverished many peasants, who switched to drug crops or became narco foot soldiers.
In January, Barack Obama met his Mexican counterpart at the White House, where both affirmed their commitment to the war on drugs. Their words had a sense of rote. Reformers contemplate regulating illicit drugs as a health measure. This week Ernesto Zedillo, Mexico's President from 1994 to 2000, argued drug consumption be decriminalised, a line taken by several leaders at the United Nations last September. At the same time some US states are legalising marijuana. Bottom line-conscious cartels are already adjusting, trafficking more profitable heroin or switching to extortion and kidnapping, ratcheting up terror levels for many ordinary Mexicans.