Long hailed as one of Mexico's safest urban area, the city of Monterrey has erupted since 2010 in an outbreak of drug violence. But behind the present crisis is a history of steadily growing organized crime in the city, which goes back many years.

In late 2010, after the mayor of a municipality in the Monterrey area was killed and dumped on the side of a highway, and a gunfight broke out on the edge of one of Mexico’s most prestigious universities, the U.S. media was flooded with accounts of Mexico’s richest city suddenly finding itself plagued by organized crime.

Carlos Pascual, the former U.S. ambassador to Mexico, furthered such reports in a speech he gave at a security conference in August. "The security environment in Monterrey has turned, in just a few months, from seeming benevolence to extreme violence," said the ambassador.

While conflicts and violence did explode in 2010, the criminal presence in the northern city that allowed for the conflagration had been building for years. Even as far back as 1997, the U.S. Drug Enforcement Agency (DEA) listed Monterrey as one of the top three Mexican cities used by drug cartels for money laundering. Attracted by the city’s large financial base and lax regulation of money transfers, the drug trafficking industry (led by the Gulf Cartel and their former security wing the Zetas) spread its tentacles into much of the city’s businesses, restaurants and real estate market.

A series of crackdowns pushed criminal syndicates to invest in one of Monterrey’s best-known assets: gambling. As La Jornada reported recently, the Mexico-based gaming association Asociacion de Permisionarios de Juegos y Sorteos has acknowledged that criminal organizations run laundering operations in at least 40 casinos in northern Mexico, most of which are in Monterrey.

Because money laundering is a relatively victimless crime, this growing criminal influence went unchecked and mostly unnoticed until around 2007, when Gulf leader Osiel Cardenas Guillen was extradited to the U.S. He left behind a power vacuum, and with no clear leader to keep the Zetas in their place, infighting soon began.

The two groups definitively split in January 2010, when Gulf Cartel members killed the high-ranking Zeta Sergio Peña Mendoza, alias "Concord 3." The Zetas demanded that Gulf leaders hand over the culprits, and when they refused, the Zetas declared war. Thus began the Zeta-Gulf feud, which is playing out across Mexico to this day, with Monterrey as its epicenter.

This battle has been accompanied by a huge spike in murders, drawing the attention of the word's media. According to a Reuters special report, this year more than 600 people have died in drug-related killings in the Monterrey area, a figure that has risen more than tenfold since 2006, when there were only 55 drug deaths.

The conflict between the two groups has been accompanied by a rise in extortion. Now, they are fighting not only for control of the "plaza," or the city’s smuggling routes to the United States, but for of total hegemony over criminal activities in the wealthy city, according to the Reuters report. Monterrey business owners are prime targets for shakedowns, and are often coerced into paying “taxes” to either of the two main criminal groups on penalty of death or kidnapping. Although these activities have not yet had a visible impact on Monterrey’s booming industrial economy, more and more companies are now eyeing the city with suspicion.

Althought the battle of the cartels is the catalyst for the current outbreak of violence, the steady increasing presence of drug gangs in the city created the tinderbox.