Authorities in the central Mexican state of Hidalgo say the suspects, who confessed to be lookouts for the Zetas drug cartel, led them to the police officers.
State police chief Damian Canales says the arrests began Sunday in the mountains of Hidalgo, where police detained six suspects who claimed the police chief and other officers offered them protection.
In Pachuca, the state capital, police also arrested simultaneously three men who were spying on police operations. Arrests concluded Tuesday with the detention of six more suspects.