Authorities say the leader of Mexico's main leftist party in the southern state of Oaxaca has been found slain, little more than a week before local elections.

The Oaxaca attorney general's office says the body of Nicolas Estrada Merino was found Thursday in a sugar cane field near the city of Tuxtepec. It says in a statement that Estrada had three gunshot wounds to the head and it's investigating the circumstances of his death.

The national leadership of his Democratic Revolution party condemned the killing and demanded that authorities speed the investigation.

Estrada was missing for more than two weeks. His car was found burned on July 16. Local elections for state representatives and mayors will be held July 7 in 14 of Mexico's 31 states.