Message received. Cool if we just grab the head and go?
The incident came as 16 other people were also killed in Mexico's northern state of Chihuahua in attacks the authorities believe are linked to the country's drug wars.
"Hitmen cut off commander Martin Castro's head and left it in an ice cooler in front of the local police station," said a statement issued by the state justice authorities.
His head was left in the town Praxedis with a message from the powerful Sinaloa drug cartel.
The police commander was abducted on Saturday, along with five other police officers and a civilian, only five days after starting his job.
Six bodies in police uniforms bearing signs of torture and gunshot wounds were found on Monday in a street in the state capital, Chihuahua, officials said.