The Mexican army says it has arrested a man who worked closely with the country's top drug dealer, Joaquin "Shorty" Guzman.
Hermilo N, also known as The Duck, was arrested in the western city of Culiacan, in Sinaloa state.
The authorities say his job was to bribe officials to gather classified information on future military operations against the drug gangs.
He is also accused of coercing judicial authorities.
Mexico's defence secretary says Hermilo N attempted to obtain the release of jailed members of the criminal organisations controlled by Guzman, Mexico's most wanted drugs lord.
The authorities say Hermilo N's capture will hamper the operations of the Pacific Cartel, which operates in association with the Sinaloa Cartel.
The gangs smuggle tons of cocaine, marijuana and other illegal drugs into the United States.
The Mexican authorities said Hermilo N was detained on 11 August, but information about the arrest was only made public on Friday.
They say weapons, ammunition and drugs were seized during his arrest.
Joaquin Guzman, known as "El Chapo", or "Shorty", was arrested in 1993.
But he has been in hiding ever since he escaped from his maximum-security prison in a laundry basket in 2001.
The US state department has offered a reward of up to $5m (£3.2m) for information leading to his arrest.