MEXICO CITY, Mexico (CNN) -- Federal agents arrested 92 municipal police officers accused of providing information and security to one of Mexico's most ruthless drug cartels, the state-run Notimex news agency reported.

The arrests occurred Wednesday in the city of Hidalgo in central Mexico after an investigation that started in October, Notimex said Thursday.

So far, the news agency said, the investigation has led to the arrests of 124 suspects and the discovery of 12 safe houses in which 14 secret graves were found.

Officials say the Zeta drug cartel is responsible for many of the kidnappings, extortion and drug trafficking in Hidalgo.

The Zetas were paying the Hidalgo police officers 3,000 to 5,000 pesos ($228 to $380) every two weeks, Notimex said.

All About Drug Trafficking • Mexico