Investigators in Mexico believe that the 49 headless bodies found on the side of a highway in the municipality of Cadereyta on Sunday morning may have been the latest victims of a war between rival drug gangs Los Zetas and the Gulf Cartel.

The discovery in the Nuevo Leon state may have been part of Los Zetas' plan for a Mother's Day massacre, according to Borderland Beat, a prominent Mexican narco-blog, while Rantburg's Chris Covert reported that some of the victims had gang tattoos.

Since journalists are often the targets of the cartels' wrath -- the body of journalist Otto Rene Salgado Orta, a police reporter with 20 years of experience who was tortured to death in Cuernavaca, was also discovered on Sunday -- Mexico's bloggers have taken up the duty of reporting on the drug war.

The bodies were found around 4 a.m. on a highway linking Monterrey and the border-town of Reynosa. Many of the bodies had been stuffed into black garbage bags, and the heads, hands and feet of the victims have not been found at the site, the Associated Press reported, making the job of identifying the bodies difficult for investigators.

According to reports, the victims could have been killed up to two days before they were discovered, and the bodies were likely transported to Cadereyta from elsewhere.

Los Zetas, which is now in contention with the Sinaloa cartel to be Mexico's largest and most violent trafficking gang, has already claimed responsibility for the murders, in a sense. On a white stone arch, where the bodies were discovered, was spray-painted the message 100% Z, which police have taken to be a reference to the gang, which often leaves messages signed Z at crime scenes to intimidate both authorities and rivals.

These notes, called narcomantas, have also been left on the bodies of dead Zetas members, believe to have been killed by the Gulf Cartel. The Gulf Cartel recently began an alliance with the Sinaloa cartel, according to global intelligence company Stratfor, and the resulting battle for territory with Los Zetas has resulted in scores of deaths and widespread violence.

Large body dumps like the one on Sunday are one facet of the cartel war. Sinaloa dropped 35 bodies off a highway overpass in the middle of rush hour in Veracruz in September, and last month seven bodies were found in the city of Lazaro Cardenas with a note signed by other Sinaloa allies.

Last year, a mass grave containing 183 people was found in the Tamaulipas state, which borders Nuevo Leon. The grave was believed to have been dug by Los Zetas and the bodies belonged to migrants, tourists and civilians. In the past year, Los Zetas have also kidnapped and murdered Gulf Cartel assassins, who had been sent to Nuevo Leon, according to Borderland Beat.

Its proximity to the Texas border has made Nuevo Leon valuable territory for drug traffickers, as well as one of Mexico's most dangerous states, along with Chihuahua, Coahuila and Tamaulipas, which are also close to the United States.

This is a war between the two most powerful criminal groups in the country and their allies, Guadalupe Correa-Cabrera, who researches drug trafficking at the University of Texas in Brownsville, told the Wall Street Journal. They are fighting for control of the most strategic points and routes in the country.

Drug violence spiked in Mexico after the election of President Felipe Calderon in 2006. Calderon made the prevention of drug trafficking one of his top priorities, initiating a military-led crackdown against cartels. Since his program began, around 50,000 people have been killed.

It is evident that we are not facing common criminals. We are facing true terrorists who have surpassed not only the limits of the law but basic common sense and respect for life, Calderon said during a State of the Union address in September.