Carlos Arnulfo Flores, alias "El Flaco" ("Skinny") and "Fantasma" ("Ghost"), was detained after being slightly wounded in a shootout with soldiers in the northern state of Coahuila on Wednesday, the ministry said.

A ministry statement said Flores acted under the orders of Zetas cartel leader Miguel Angel Trevino Morales to kill Jose Eduardo Moreira, 25, last month as "retaliation" for his nephew's death in a firefight with authorities.

The victim is the son of Humberto Moreira, who was governor of Coahuila from 2005 to 2011 and chairman of the Institutional Revolutionary Party (PRI) for nine months last year. He is also the nephew of Coahuila's current governor, Ruben Moreira.

Moreira's body was found in Ciudad Acuna, a Coahuila city on the US border, on October 3 with two bullets in the head and signs of torture.

The defense ministry said that an Acuna police officer who has since been detained lured Moreira into a trap in order to hand him over to Flores and two other killers.

The officer, Rodolfo Castillo, and two other policemen were detained in connection with the case last month.