Marines arrested 19 of officers in the city of Xalapa on September 22, and the other 16 at an airport in the state of San Luis Potosi, Excelsior reported. The arrests were ordered by the unit of the Attorney General's Office dedicated to organized crime.

Veracruz Government Secretary Gerardo Buganza Salmeron said that the state would keep training new police officers under the Creditable State Police project, and that 1,600 had already graduated from the academy, reported Milenio.

Buganza said that the arrests were carried out as part of the ongoing Operation Safe Veracruz.

InSight Crime Analysis

The Zetas took control of Veracruz in 2010 after splitting from the Gulf Cartel. However, in the last couple of years its dominance has been challenged by the Jalisco Cartel - New Generation (CJNG), causing murders related to organized crime to increase four-fold in the first nine months of 2011.

The authorities have taken drastic action in their efforts to clean up Veracruz's police. In October 2011, 980 officers, more than 10 percent of the state force, were fired after failing tests designed to root out corruption. At the time, state Security Secretary Arturo Bermudez Zurita said that the government was committed to creating a "100 percent" trustworthy state police force.

There have also been problems with the municipal police. In December last year, the city of Veracruz fired its entire police force, made up of 800 agents and 300 administrative staff, replacing them with the marines.

This, and the recent arrests by the marines, indicate how much the Mexican authorities are relying on federal forces to supplement and keep in check corrupt local police. In October last year, the government deployed federal troops to the state as part of Operation Safe Veracruz. The fact that it is still ongoing, and that police continue to be accused of ties to crime despite the government's promises, indicates that cleaning up Veracruz's security forces could be a long job.