The decapitated body of a man was discovered Wednesday in the border city of Nuevo Laredo, purportedly in retaliation for his reporting on drug cartels on a popular social media site.
"This happened to me for not understanding that I shouldn't report on the social networks," read a bloodstained note left with the body.
Police found the body at a monument on one of the city's main thoroughfares, said a Tamaulipas state investigator who spoke on condition of anonymity because he is not allowed to discuss the case due to safety concerns.
A photograph of the scene posted on a blog shows a handcuffed man lying on his belly on top of the bloodstained note and a chopped head nearby.
The message claimed the man, identified only by his nickname "Rascatripas" -- meaning "Belly Scratcher" -- was a moderator of "Nuevo Laredo en Vivo," a website used by city residents to denounce crime and warn each other about drug cartel gunfights and roadblocks.
The gruesome killing may be the fourth since September in which people in Nuevo Laredo were killed by a drug cartel for what they said on the Internet.
The decapitated body of Maria Elizabeth Macias, "La Nena de Laredo," or "Laredo Girl," was found at the same site in September with a message that said she was killed for her reports on the website. That message was signed with the letter "Z," which refers to the violent Zetas drug cartel.
Earlier that month, the bodies of a man and a woman were found hanging from an overpass in Nuevo Laredo with a message threatening, "this is what will happen" to trouble-making Internet users and also signed with a "Z."
The Zetas have dominated Nuevo Laredo, located across the border from Laredo, Texas, for years.
"Nuevo Laredo en Vivo" has a message acknowledging Macias was a contributor and lauding her courage.
Chat messages on the website show a user with the nickname of "Rascatripas" commented Monday afternoon about the dangers of traveling on a riverside highway that connects Nuevo Laredo to Ciudad Mier.
Whether the unidentified man found Wednesday at a monument to Christopher Columbus contributed to the website is unclear.
"We have no way of confirming whether He is the person who was killed because we're all anonymous," said a tweet by "Nuevo Laredo en Vivo" in response to a request for comment by The Associated Press.
Still, users of "Nuevo Laredo en Vivo" vowed to continue reporting criminals to authorities.
"Those guys think they are so smart. They want to spread fear," one user wrote Wednesday night. "As long as no one confirms Rasca was an honest citizen, let's leave it as a doubt and continue on."
According to the Houston Chronicle, another post written after the man's death declared: "Let's continue denouncing them, now that we've seen it burns them, hurts them....We have to continue. We can't give in."
You can watch a Spanish-language KLDO-TV report on the body's discovery below, featuring images from the crime scene:
The Associated Press contributed to this report.