Mexico’s authorities are now saying a massacre at a Mexico prison was part of a sophisticated prison break involving guards. Thirty alleged members of the Zetas escaped, including “El Arana,” head of the Monterrey plaza.

The governor of Nuevo Leon state, Rodrigo Medina de la Cruz, said that the government would pay a $785,000 reward (10 million pesos) for information on the location of the escapees from Apodaca prison. They are thought to include Oscar Manuel Bernal Soriana, alias “El Arana,” the boss of the Monterrey “plaza,” or drug trafficking territory.

According to news website Frontera, the escape was carried out through an elaborate plan that enabled the 30 or so inmates to escape in just 20 minutes, with the killings taking place in the immediate aftermath when a group of Zetas inmates were allowed to pass, armed, to the block housing members of the rival Gulf Cartel.

Initial reports suggested that prison staff had colluded in the attack, and these appear to have been confirmed with at least nine prison guards admitting to being complicit in the incident, according to state security spokesperson Jorge Domene. The director of the prison, along with several other officials and 18 guards, has been removed.

Details have also begun to emerge on the identities of the dead with reports claiming most, if not all, belonged to the Gulf Cartel. The number of prisoners that fled remains unclear, however, with some putting the number at 30 and others at 33.

InSight Crime Analysis

The workings of this particular escape point to worrying levels of collusion between prison officials and the Zetas, and again shows that Mexico’s authorities are not immune from taking sides in inter-cartel battles.

This corruption can be traced back to institutional weaknesses in Mexico’s penal system. With only six federal prisons throughout the country, many high-ranking, and highly dangerous, inmates are sent to state penitentiaries. Some state governors, like Nuevo Leon’s Medina, complain of their inability to house such powerful criminals, as the Associated Press notes.

The Apodaca escape is at least the second time in recent months that prison staff have been accused of being complicit in the escape of Zetas members, with at least 18 staff detained following the escape of 11 alleged members in the state of Puebla.

A group of alleged Zetas were recaptured in a cartel training camp in Veracruz in October, after breaking out of prison the previous month.