A leftist candidate running to become a federal lawmaker in Mexico's upcoming mid-term elections was killed on Tuesday, in the latest example of deadly violence in the run-up to the vote.
Miguel Angel Luna, of the leftist Party of the Democratic Revolution (PRD), was shot dead by armed assailants in his campaign office in Valle de Chalco, a populous suburb of Mexico City, the attorney general's office for the state of Mexico said.
Eloi Vazquez, a PRD spokesman, said he did not know whether Luna had received any prior threats.
Since March two candidates running in mayoral races have been slain in the southern states of Michoacán and Guerrero and a third woman who was planning to run in Guerrero was killed.
On Sunday, Mexican President Enrique Pena Nieto faces his first national vote since winning the presidency in 2012.
The lower house, nine governorships and various state legislatures are up for grabs.
In the run-up to the vote, 16 candidates have been killed, with recurring threats of boycotts and disruptions from unions and criminal groups.
Radical groups and unionised teachers have vowed to block Sunday’s voting for the lower house of congress, nine governorships and hundreds of mayorships.