A regional security chief in the Mexican border state of Tamaulipas has been shot to death along with his wife, authorities said

It was the latest round of violence affecting Tamaulipas, which is across the border from Texas. The dead man, Gen. Ricardo Niño Villarreal, was security chief for the area around Nuevo Laredo, across the border from Laredo, Texas. The area is considered the turf of the Zetas drug cartel, which has been doing battle with the Gulf cartel. Gen. Niño Villarreal was one of several ex-military officers tapped to serve as regional commanders as part of a plan announced in May to stem a wave of violence in Tamaulipas. The state government said that the killing took place on a roadway in neighboring Nuevo Leon state. However, it wasn’t until the next day that passersby noticed the couple’s car and alerted police. The car was a compact model and the couple was traveling on a non-toll road that links Nuevo Laredo to the industrial hub of Monterrey. The state government said that armed assailants ambushed them. Despite the government plan for beefed-up security, violence has continued in Tamaulipas. Recently, residents, lead by priests and clad in white, marched through Ciudad Victoria, carrying photos of people who have disappeared due to kidnappings and drug-gang violence. The protesters estimated that at least 750 people have been killed or disappeared in the area over the past four years. Roman Catholic Bishop Antonio Gonzalez Sanchez questioned whether any progress was being made. “What good have those signatures done? I am just asking that question,” he said. Recently, investigators found the bodies of three U.S. citizens and another man who had been shot to death near the city of Matamoros, in Tamaulipas. The Americans had been reported missing on a visit to Mexico a couple of weeks before. The fourth body is believed to be the Mexican boyfriend of one of the slain Americans. Tamaulipas officials have said that they were investigating a possible police connection to the deaths. The family of the Americans has said that witnesses reported they were taken away from a restaurant by armed men who identified themselves as part of the “Hercules” tactical security unit in Matamoros. Each of the four dead had been shot in the head and the bodies were burned, most likely from the sun.