By Ioan Grillo
MEXICO CITY, May 20 (Reuters) - Mexican soldiers have arrested an alleged perpetrator of the massacre of 49 people whose corpses were decapitated, dismembered and dumped on a highway last week.
Daniel Elizondo, alias "The Madman," a leader of the Zetas drug cartel, was detained in the northern state of Nuevo Leon, a spokesman for the army said Sunday.
Elizondo headed the Zetas trafficking operations in Cadereyta, an industrial town on the outskirts of Monterrey, close to where the bodies were dumped, the official said.
The massacre is one of the worst atrocities committed in Mexico's drug war, which has raged since President Felipe Calderon took power in 2006 and launched a national offensive against the cartels.
Police found the corpses on the highway about 18 miles (29 km) east of Monterrey on May 13. As the bodies lacked heads, hands and feet, police said they could only identify them using DNA. A week later, none of the victims has been identified, according to investigators.
Police said they have found no signs of recent mass disappearances in the region and the victims could be migrants from Central or South America passing through Mexico on the way to the United States.
Drug cartels often kidnap foreign migrants for ransom, killing those who do not pay.
Graffiti sprayed at the scene of the corpses showed the mark of the Zetas, who are fighting for control of the region.
A video that allegedly shows the men dumping the bodies was also posted on the internet. In the film, men can be seen pulling a large pile of corpses from a truck onto the road during the night. They are then seen leaving a message on a blanket that threatens security forces and the rival Gulf and Sinaloa cartels of traffickers.
"Gulf cartel, Sinaloa cartel, marines and soldiers, nobody can do anything against us or they will lose," said the message, which was signed by names of Zeta leaders.
However, in the following days, messages were put up in several Mexican states claiming the Zetas were not behind the massacre - an unusual measure as the gang openly claims to be behind many mass killings.
The Zetas were founded by former soldiers who defected from the Mexican military in 1998 to work as hired killers for drug traffickers. They have since carved out their own smuggling empire, expanded massively across Mexico and diversified into kidnapping, extortion and theft of crude oil.
In recent weeks, violence between the Zetas and their rivals has intensified in several parts of Mexico.
Among the worst incidents, 18 people were decapitated near the city of Guadalajara and nine victims were hanged from a bridge in the city of Nuevo Laredo, across the border from Laredo, Texas.
In total, around 55,000 people have died in drug related violence and more than 5,000 have disappeared in Mexico since Calderon took office in December 2006.
(Reporting By Ioan Grillo; Editing by Vicki Allen)