An opposition politician elected in Mexico's July 1 vote and his campaign manager were found shot to death in a truck early Sunday morning in the central state of San Luis Potosi, which has seen a spike in drug gang-related violence in the past week.
Edgar Morales, a member of the Institutional Revolutionary Party (PRI) who won the mayoral race in Matehuala, and Juan Hernandez were ambushed by gunmen after leaving a birthday party in the town, the state attorney general's office said in a statement.
Authorities found spent rounds from high-powered rifles at the scene, the statement said.
Hernandez's wife, who survived the ambush, did not see the gunmen, and authorities have not established a motive for the murders, said a government spokesperson who requested anonymity for security reasons.
Morales who ran on a coalition ticket between the PRI and smaller Green Party, narrowly defeated a candidate from outgoing President Felipe Calderon's National Action Party, according to state election data.
The PRI won the country's presidential election.
In a statement from its San Luis Potosi state office, the PRI demanded that authorities find and punish the gunmen.
Morales' murder followed the discovery of 14 corpses early Thursday in a van on a major highway outside the state capital, also called San Luis Potosi, located about 124 miles south of Matehuala.
The abandoned bodies bore the hallmarks of drug cartel violence. Gangs are battling over control of trafficking routes to the United States, but officials have not identified which group may have been responsible for the latest attacks.
San Luis Potosi also saw an hour long shoot-out with gunmen on Thursday after police raided a alleged drug cartel safe house.
More than 55,000 gangland murders and execution-style hits have occurred since Calderon took power in December 2006 and declared a national crackdown on drug gangs.
(Reporting By Michael O'Boyle and Tomas Sarmiento; Editing by Paul Simao)