Police in Mexico have found eight decapitated bodies in the northern state of Durango.
Among the dead was the deputy governor of Durango's prison, who had been abducted on Monday.
Gerardo Galindo's head was found next to a wall bearing a threatening message by a local drug gang.
Prison officials are increasingly being targeted by drug gangs, whose jailed members often continue to run their businesses from behind bars.
In February, the security chief of a prison in the northern city of Monterrey was murdered.
His dismembered body was found in a plastic box inside a car abandoned near the prison he worked at.
Officials have not yet identified the remaining seven bodies found in Durango.
Forensic experts also uncovered another eight bodies in mass graves in Durango city, the state's capital, bringing the total discovered over the past month to 196.
Durango state governor Jorge Herrera Caldera said on Wednesday that he thought most of those buried in the mass graves had fallen victim to a "settling of scores" between drug gangs.
The state's murder rate has risen steeply in recent years as rival gangs battle for control of the drugs trade in the area.