MEXICO CITY (By Ioan Grillo, Time) September 9, 2008 ― There's a peaceful aura about the lifeless faces lined up on the video, death having drained the tension from their cheeks, their eyes wide shut above thick mustaches and square jaws. But as the shot pans out, the horror of their end is revealed: The dead men's heads have been roughly hacked away from their torsos, which the camera finds hanging upside down across the room on meat hooks, their blood draining away onto white floor tiles. "This is your responsibility for not respecting the deals you have made with us," reads a handwritten note in Spanish by the decapitated heads.

The sickening footage was posted on YouTube after 12 headless bodies were dumped onto two ranches in Mexico's southeastern Yucatan peninsula last week. Police identified the victims as local drug dealers, saying five were decapitated while alive but that the rest had been dismembered after first being strangled or beaten to death. A police sweep netted three suspects allegedly arrested while carrying bloodied axes and machetes. The suspects were alleged to have been members of the ultra-violent drug gang the Zetas, indicating the atrocities may have been the latest act of terror in the relentless turf war over Mexico's billion-dollar smuggling routes. Police also claimed the killings may have had a ritual dimension, after searching the suspects' houses and finding shrines to "The Holy Death," a Grim Reaper figure venerated by many Mexican criminals.

The biggest mass beheading in recent history caused widespread revulsion in Mexico but little surprise. Decapitations have become as commonplace in the increasingly vicious narco turf battles as stabbings are in London. During August alone, gangsters hacked off 30 craniums across the country — adding to the total of almost 200 beheadings in 2008 so far. Heads have been stuck on crosses, shoved into iceboxes and left in car trunks along with snakes.

"The gangsters use these bloody tactics to try and win a psychological war against their enemy and sow terror in the population," says Luis Astorga, author of several books on the cartels. "But neither side is winning, and the violence just spirals without end as the gangs keep raising their bets and killing in more spectacular ways."

Decapitations were almost unheard of here before 2006. The first case related to the drug wars occurred in April of that year, when thugs left the craniums of two policemen in the seaside resort Acapulco, apparently in revenge for the shooting of four traffickers in a prolonged gun battle. The following September, thugs in ski masks rolled five severed heads onto a dance floor in the mountainous state of Michoacán. The cycle of beheadings intensified throughout 2007 until every gangster in Mexico seemed to have an executioner's ax in his arsenal.

Most heads are left with notes, such as one that read: "See. Hear. Shut up. If you want to stay alive." Others have been videotaped, the footage posted on the Internet. One 2007 film on YouTube showed a man in a ski mask slicing off the head of an alleged Zeta in his underwear tied to a chair. YouTube quickly removed the video, just as it took down last week's film of the beheaded bodies. But the site handles millions of videos, making them difficult to control.

Public Safety Secretary Genaro Garcia Luna claims the inspiration for the terror tactic had been al-Qaeda in Iraq. "This began after there was an image that al-Qaeda sent out to the world via the Internet showing the execution of a prisoner in Iraq," he told a news conference after the 2007 video.

There may also be more local influences at work. Following some early beheadings, Mexican police arrested former members of Guatemala's élite Kaibil military unit, which carried out bloody atrocities against rebel villages during the nation's four-decade civil war. "We have testimonies of the Kaibiles hacking off the heads of living people with knives to terrorize communities," said Guatemalan Representative Otilia Lux de Coti, who served in the nation's Truth Commission following the 1996 peace accord. "Many continue to be dangerous killers after they leave the military." The Kaibiles are alleged to work with Mexico's Zetas, many of whom were themselves defectors from élite military units. Beheadings are also a favored tactic of Central America's bloody Mara Salvatrucha gangs, who have been enlisted as muscle by the Mexican mafias.

Archaeologist Ernesto Vargas says the tactic could even reflect the pre-Columbian use of beheadings, a common tactic of the Mayan people who dominated southern Mexico and Guatemala before the Spanish conquest. "The Mayans cut off the heads of prisoners as a symbol of complete domination over their enemies," Vargas says. One of the biggest pre-Hispanic sites of severed skulls was found in the Mayan ruins of Chichen Itza, close to the site of last week's massacre, he points out.

Whatever its roots, there appears no end in sight to the current wave of decapitations. Astorga fears that even worse atrocities lie ahead. "Who knows what perverse methods these assassins might use to get one up over their rivals," he says. "Many are military killers but without the army command to hold them back. Their only limits are what they can imagine or what they can find in the most violent Hollywood movies."