Investigators don't have a motive yet, but the former chief had operated a private security company. Drug cartels are fighting over turf in several Texas-Mexico border towns, including Nuevo Laredo.
When we crossed into Mexico on Monday, we had a strong warning from U.S. Border Patrol.
"Be careful," the agent said, "You're going into a war zone."
When we got into Mexico, into Nuevo Laredo, we were first greeted by a Mexican soldier who said matter of factly, "Why are you here? It's too dangerous."
But we moved forward, driving into battle zone where bodies lay in the streets.
In the middle of the day, two bodies lay in the street, riddled with bullets. It's only one of several successful hits this week by drug cartel thugs.
"Is this a battle that is not going to be won by the Mexican government?" we asked Tomas, a former cartel thug.
"No, this is going to take years and years -- generations," he replied.
Tomas knows the power of the Zeta Cartel. He openly admits his deadly work in Mexico and in Texas for the cartel.
"Like I say, they know me. They come for me, just like that. There's no law around," Tomas said.
After spending time in a Texas prison, Tomas is back in Mexico, watching this time, as the cartel's influence spreads like wildfire.
"How powerful is the cartel?" we asked him.
"I think they are more powerful than the government," he said.
Just one look at this town of Nuevo Laredo and it's clear who is in control. The cartel killings are everywhere and local police are nowhere.
"It seems as though the drug cartel can pay off everyone, from the lowest to the highest. Is that true?" we asked Tomas.
"That's true," he replied.
Police officers in this town were given an edict, plato o plomo, silver or lead -- cash to keep quiet and play along with the cartel or a bullet to the head.
The officers were fired or quit and soldiers have replaced them. But residents here have no love for the military.
"Who's going to help us? Nobody. We don't have police. The people want the police back to the streets," a Mexican journalist named Susana said.
The fear here is so thick, nobody wants to go on camera. Even soldiers run when they see us. We followed some soldiers as they raced away, reaching speeds of nearly 100 miles an hour.
"The authorities," Susana said,"they don't do anything."
So the violence increases, reaching extraordinary levels, with bodies being found mutilated in the streets and warnings from the cartel to not get involved.
By nighttime, the streets are nearly empty, and Mexicans everywhere are clearly on edge. A lot of them didn't want to talk on TV.
Reporting on the cartels is not an easy job.. In fact, it's a deadly one. Over the past two years, three dozen Mexican journalists have been killed.