A candidate for Mexico's Congress from Coahuila state, Fernando Puron, was shot dead in the city of Piedras Negras on Friday night, immediately after the debates, local media reported on Saturday, Sputnik reported.

Puron stood outside the building of a state university with a woman who asked him for a photo when a killer approached him from behind, fired a shot at the back of the head and fled the scene, El Universal newspaper reported, publishing a CCTV video of the incident.

Puron was nominated to the elections, which will be held on July 1, from the ruling Institutional Revolutionary Party.