Authorities in northern Mexico will request greater military assistance from the central government in the face of a recent surge in violence, as concern mounts over the possibility of renewed upheaval in a region once controlled by the Zetas.

The Nuevo Leon Congress, based in state capital Monterrey, voted to request a further deployment of marines and soldiers after a reduction in troop numbers was followed by an increase in insecurity. According to Juan Carlos Ruiz of the National Action Party (PAN), crimes such as extortion and murder have risen as organized crime has become more active, reported Vanguardia.

However, Rear Admiral Augusto Cruz Morales, the Monterrey security minister, said federal troops planned to further reduce their presence in the state capital as part of continued “restructuring,” reported Proceso.

While some Nuevo Leon authorities insist insecurity has not increased, a recent survey found 84 percent of residents in the Monterrey metropolitan area felt insecure. According to state officials, September had the lowest monthly murder rate since 2010, but in the same month Terra reported rampant extortion and the killing of local merchants.

InSight Crime Analysis

The Zetas seized control of Monterrey from the Gulf Cartel in 2010, during the first year of their split and the bloody power struggle that followed. However, by late 2012, the Gulf Cartel had capitalized on turmoil within the Zetas ranks — exacerbated by the death of leader Heriberto Lazcano — and regained control of much of the Monterrey greater metropolitan area. As the Zetas lost their grip on the city, officials reported declining homicides.

SEE ALSO: The Zetas and the Battle for Monterrey

Since then, both organizations have lost their top leadership and have become increasingly divided. Miguel Angel Treviño, alias “Z40,” who took over the Zetas following Lazcano’s capture, was arrested in July 2013. The head of the Gulf Cartel, Mario Ramirez Treviño, alias “X20,” who had consolidated control of the organization by taking out his internal rival in January, was arrested in August.

These captures have resulted in a power vacuum in north Mexico, opening the way for a new struggle for control over this drug corridor.

Whether this vacuum is causing violence in Monterrey is difficult to assess. Officially, just 540 homicides occurred from January to August 2013, compared to 1,111 in the same period the year before, but the media has accused the state government of distorting figures to boost their image and Proceso reported that violence in Nuevo Leon began to resurge in August, despite claims to the contrary by the governor.