PIEDRAS NEGRAS, Coahuila – Residents of this border city remain fearful amid an escalation of violence featuring shootouts and gory executions.

Despite the assurances given by officials, cartel gunmen continue to operate throughout northern Coahuila and carried out a series of attacks against police checkpoints along the highway that connects Piedras Negras and the border city of Nuevo Laredo. In addition to the attacks, cartel gunmen have left severed heads with threats to law enforcement.

During his recent visit to Piedras Negras, Coahuila Attorney General Gerardo Marquez Guevara confirmed to Breitbart News that out of the seven murders in the city, authorities are close to solving two of the cases. According to Marquez, his agents are working with counterparts at the national level and with U.S. law enforcement to locate suspects.

“The order is very clear,” Marquez said, “we have to clear up each of the violent deaths in the border region.”

The Cartel Del Noreste (CDN) faction of Los Zetas has been carrying out a series of executions in Piedras Negras and Ciudad Acuna to intimidate law enforcement. Cartel gunmen have left severed heads warning informants and state police that they too would meet a similar fate. This push by the CDN is similarly seen in the border states of Nuevo Leon and Tamaulipas. In each of those states, the CDN is working to take control of local drug distribution and routes into Texas.

Editor’s Note: Breitbart News traveled to the Mexican States of Tamaulipas, Coahuila, and Nuevo León to recruit citizen journalists willing to risk their lives and expose the cartels silencing their communities. The writers would face certain death at the hands of the various cartels that operate in those areas including the Gulf Cartel and Los Zetas if a pseudonym were not used. Breitbart Texas’ Cartel Chronicles are published in both English and in their original Spanish. This article was written by “J.M. Martinez” from Coahuila.