Mexico City  - The speaker of the lower house of Mexico's Guerrero state legislature was shot dead Thursday, the authorities said in state capital Chilpancingo.

The police report said Armando Chavarria Barrera was found dead in front of his home, in the passenger's seat of his vehicle. He had been hit by two bullets.

Chavarria Barrera, of the state's ruling leftist Party of Democratic Revolution (PRD), was considered a potential candidate for state governor.

In a separate incident on Thursday, three human heads were found in three coolers in the town of Coyuca de Catalan, also in Guerrero, the local Public Security Ministry said.

Two black bags and a blanket holding dismembered human body parts were found near the coolers. The authorities believe these may be the three bodies that correspond to the dismembered heads. A piece of paper with a message had been left by the gruesome finding, although the authorities did not disclose its content.

More than 4,400 people have died in Mexico since January in incidents linked to organized crime and drug trafficking. (dpa)