Mexican police video of the arrest of Antonio Galarza on suspicion of weapons violations and money laundering
Eleven policemen have been killed in a weekend of drugs-related violence in the Mexican state of Michoacan.
It remains unclear if the murders, which occurred on roads and at police checkpoints around the state, were part of a coordinated plan.
Police have arrested 10 people in connection with the killings.
Mexico is suffering from widespread drugs-related violence, with more than 2,700 people shot dead this year as rival cartels battle for supremacy.
Mexico State prosecutor Alberto Bazbaz said the suspects were connected to drug gangs, adding that some were carrying rifles and grenades at the time of their arrest.
It remains unclear whether they were part of a cartel known as La Familia, which is said to control the illegal drugs trade in the state.
Meanwhile, police in the northern city of Monterrey arrested Antonio Galarza, the alleged leader of the powerful Gulf Cartel.
The gang controls a large part of the multi-billion dollar flow of drugs from Mexico to the US.
Earlier, one of Mexico's most senior police officers resigned amid allegations that drugs cartels may have infiltrated the highest echelons of the Mexican security and police forces.
Acting Federal Police Commissioner Victor Gerardo Garay stood down after one of his aides was accused of working for the Sinaloa drug cartel.
The resignation suggests there may be more truth in allegations of police infiltration by drug gangs than the government has acknowledged, says the BBC's Americas analyst Emilio San Pedro.