Freedom of expression continues to come under attack in Mexico. This week, Mexican President Felipe Calderon announced that his government is exploring "all options to proceed legally against those who have denounced the government in international forums and in the courts." This announcement came in response to a complaint filed by Mexican activists and signed by over 23,000 Mexicans, in International Criminal Court last week, demanding that the court investigate alleged human rights violations by the army and the police as part of the state's war against the drug cartels. Reports indicate that the Calderon government is considering legal action not just against Netzei Sandaval, the human rights attorney who filed the complaint with the ICC in the Hague, but also against the 23,000 individuals who signed their names to the petition online.  This is deeply troubling, as it could result in a profoundly chilling effect on political speech in Mexico. 

In the meantime, Twitter users continue to face government harassment. Mareo Flores (@mareoflores) was detained by police earlier this month, based on a series of joking tweets he made shortly before Mexico's interior minister, Francisco Blake Mora, and seven other officials were killed in a helicopter crash. According to his father, Mareo was arrested two days after the crash when he was taken away by men in five unmarked black cars.  He was released a few hours later after prosecutors interviewed him. Law enforcement officials have faced criticism stemming from the arrest, especially because the official investigation indicated that the crash was an accident rather than an assassination. 

If the Mexican government seems overly sensitive about what its citizens are saying online, they pale in comparison to the Zeta drug cartel, which continues its campaign of terror against social media users in Nuevo Laredo. Earlier this month, the decapitated body of a man was found dumped one mile from the Texas border. A message written on a blanket found beneath the body read: 

Hi, I am 'Rascatripas' and this happened to me because I didn't understand that I shouldn't post things to social networks.

"Rascaptripas" or "Fiddler" was the nickname of a moderator on social networking and news site Nuevo Laredo en Vivo. An editor for the website was confirmed murdered two months ago. Her decapitated body was dumped in the same location, along with a similar warning. Despite initial reports to the contrary, the identity of the newest murder victim remains unconfirmed. Nuevo Laredo En Vivo has announced on Twitter they have no connection to the man:

Negative, he was not our partner, he is confirmed to have been a scapegoat to scare others. The person executed is not a collaborator with our site, but this was without a doubt an attempt to silence the voices of Nuevo Laredo.

While the facts of this case are still unclear, there are a number of alarming possibilities. Nuevo Laredo en Vivo may be denying their connection to the murdered man in order protect themselves, in which case the Zetas may have used online surveillance to discover the identity behind Rascaptripas. If that is the case, social media users writing about drug violence in Mexico should be especially vigilant about maintaining their anonymity. Websites that host forums and chat rooms in which people discuss drug violence should review their security, enable HTTPS support, and encourage people to take stronger privacy precautions such as using Tor to connect to their site.  Users must begin using pseudonyms and be very careful about reveal too much about themselves. If drug cartels have chosen to turn their considerable resources towards Internet surveillance, this murder could be the start of a very dangerous trend. 

Another possibility is that the Zeta cartel has not made inroads into Internet surveillance at all--they actually don't have to. They could have murdered the wrong man, or they may not have made any effort at all to find the right man. The message that drug cartels are willing to mutilate and kill at random in order to silence criticism on social networks is just as much of a deterrent as the murder of real bloggers and moderators. Terror is the point. The Zetas don't have to be accurate, they just need to be brutal. Worse still, if the killings are random, then there are no concrete technical steps that social media users can take to protect themselves. 

But social media users in Mexico will not be silenced. Shortly after the murder, a poster to Nuevo Laredo en Vivo wrote:

Let's continue denouncing them, now that we've seen that it burns them, hurts them...We have to continue. We can't give in.

For those that are still posting, taking steps to protect their security and anonymity are more important than ever.  EFF will continue to provide the tools and knowledge to help Mexican citizens protect their privacy and anonymity in this confusing and potentially risky environment.