(CNN) -- It wasn't the sight of tortured bodies that scared "Chuy." It was what was written on the sign that was left next to them.
"This will happen to all the Internet snitches." It was signed by Los Zetas.
The banner was placed next to the two victims, a woman and man, both in their 20s, both gruesomely killed. The woman was disemboweled, left with her intestines protruding from her belly. They were found in September 2011, hanging from a bridge in Nuevo Laredo, Mexico, robbed of any future dignity.
About three hours away in Reynosa, Chuy's stomach grumbled when he saw the banner on the Internet. "Those people hanging from the bridge could have been me," he thought.
For the past two years, Chuy has taken to Twitter to act as a tipster to cartel activity in his town. When local and state authorities tried to downplay news about the cartels operating in the northern Mexican state of Tamaulipas (at one point the government attributed the tension to the "psychosis of the residents") Chuy was one of the first people on social media to tip the world about what was really happening.
His news of "narco blockades" and gun fights throughout Reynosa in late February 2010 was among the first news people received about the fresh war that erupted between Los Zetas and the Gulf cartel. He has become such a trustworthy source of information that the social media savvy residents of Reynosa head to his account to find what places to avoid before leaving their homes. Others trapped in the street after gunfights look to him to offer alternate ways to get home. His account has become both a tool of information and survival. He asked CNN not to use his name to protect his identity.
"During an attack, the network goes beyond Twitter. People on the street send me an SMS alert, a radio alert or a phone call to let me know what's going on," Chuy says of his role of protecting Reynosa's innocent. "We continue to report after the attack to cover the information gap by the local press.
"Thanks to Twitter we have documentation, with video, audio and images, of violent events," he says. "It's a registration [countering the] opacity and denial of local and state government.
"Many people have trusted me and I appreciate it," he says. "It's very rewarding and a great responsibility that motivates me to make sure I use Twitter properly ... as a tool of social utility."
Chuy is well aware of his responsibility. The short description on his Twitter account makes that clear, "A society [that is] selfish, apathetic, indifferent has no moral authority, it is more comfortable complaining, blaming, criticizing than participating [to] contribute, [to] build..."
Inspired in part by the "Green Revolution" in Iran, Mexican citizens became increasingly active on the social media site in 2010 as a way to combat the drug violence infesting their cities. Lacking confidence in their local authorities, they took Twitter to "spread truth," denounce cartels and warn each other of shootouts.
On YouTube, a video titled "Cartel De Twitter" gives guidance on how to create anonymous Twitter accounts so users can announce where cartels are operating. It gives examples of how to circulate information to a wider audience by using hashtags and how to direct tweets to legitimate journalists on Twitter.
In some cities of Mexico -- especially in the northern part of the country -- cartels have used violence and intimidation to control swaths of land and smuggling routes in their unquenchable quest for money and power. Their assault on Mexican bloggers seemingly takes aim at controlling cyberspace as well. For many within the blogging community the development comes as no surprise. Some were even anticipating it.
Chuy wasn't always so plugged in. Before the cartels used his town as their battlefield, he spent the majority of his days at work. Born into a family of traders in Mexico City, he moved to Reynosa a few years ago to follow his passion and open up his own store.
He would use the Internet sparingly, most of the time to play games or stay in touch with friends back home in the capital. He has always been low key, passing the time at weekend carne asadas with friends or going to the movies. Life is radically different now.
"I avoid the street at night," he says of the unofficial curfew local residents adhere to in Reynosa. He speaks in a hushed tone, choosing his words carefully before delivering them. His voice is delicate, but soaked in concern.
"If you go to a party, you sleep there. If not, you might suffer an attack by armed civilians if you come across the wrong people on your way home."
In Reynosa, the bad guys aren't always so easily recognizable. Chuy says most residents are suspicious of the public security forces. "They will, under any pretext, extort you," he says of the authorities.
About a year ago the hashtags frequented by Chuy were saturated with tweets about his confrontation with the local police. His friends messaged the media, asking for news outlets to cover the assault. They cited it as a microcosm for what everyday residents go through. When asked by CNN what happened, Chuy downplayed the incident, saying instead it's what to be expected "in the environment of corruption and war."
"They roughed me up outside of my store ... The police are the more visible arm of the local cartel," he says, as if asked to state the obvious. "Everyone knows that."
When asked about the specific allegations of corruption, CNN was referred by local authorities to the Tamaulipas Attorney General's Office. After repeated requests for an interview, CNN did not receive a response. In past interviews conducted by CNN with attorney general's spokesman Ruben Dario Rios, similar allegations of abuse among local and state officials were denied.
Chuy says the incident with the police was the only "direct threat" he's received. But in a part of the world where talking about threats is enough to get you killed, it's no surprise he is shy when the subject comes up.
"I think there is a real risk [to my life]", he says. "Sometimes you get that feeling, so you have to maintain a low profile. In Reynosa, one slip-up can cost a lot. It's not a place where people feel comfortable asking the police for help staying safe," he says.
As for those who are trying to keep people like him silent, Chuy addresses it with indignation. His defiance is clear with every tweet he sends.
"They try to silence the voice of citizens with their organization through fear, terror," he says. "Obviously what we do affects the interests of the cartel and local government. But the citizens have found a way to organize and protect each other on Twitter. The police and authorities ... they don't care. So you find a way take care of them."