Editor's note: This article is part of "Underworld: a global crime blotter," a semi-regular series covering crime and punishment around the world.

GUATEMALA CITY, Guatemala – The scene was shocking even for a country made cold to horror: 27 bodies, hands bound, all but one decapitated, spread around a cattle ranch and a note written in a victim’s blood.

The note was signed by a cell of the Zetas, one of Mexico’s feared drug cartels.

It was the worst massacre in years, its brutality reminiscent of the tortures carried out during the 36-year civil war that ended in 1996.

For Guatemalan officials, it was yet another sign that Mexican drug gangs were raising hell in Guatemala. “It is a despicable act which, we believe, was run by the Zetas,” said Interior Minister Carlos Menoca.

Not long after taking office in 2008, President Alvaro Colom began to warn that Mexican cartels, namely the Zetas, were moving south as Mexico’s drug war intensified. After the massacre, he told Spain’s El Pais newspaper, "The fact is, they are invading us."

Yet, when authorities caught 16 of the alleged perpetrators last month, a murkier and more realistic portrait of the face of cartels in Guatemala emerged.

Eleven of the suspects were Guatemalans, including the alleged leader, Elder Estuardo Morales Pineda, known as "el Pelon,” slang for “the bald one.” What’s more, authorities found documents linking seven of the suspects to Hugo Alvaro Gomez, an ex-sergeant of the Kaibiles, a Guatemalan army special unit responsible for massacres during the war. He was later arrested.

As the case shows, Guatemalan criminal networks play a principal role in drug trafficking, a scourge that has caused crime rates to spike in the tiny Central American country, security experts said.

(Read: A tiny country with a big crime problem)

Guatemala “has a growing presence of Mexican drug cartels that have escalated the violence,” said Adriana Beltran, senior associate for citizen security at the Washington Office on Latin America who has studied organized crime in Guatemala. “That said, the problem of organize crime is not new to Guatemala. There is a history of the presence of criminal groups with ties to the smuggling of contraband, humans and drugs.”

More than 60 percent of cocaine on its way from South America to users in the United States passes through Guatemala. And authorities are overmatched. Last year, the government seized just 1.4 metric tons (roughly 3,000 pounds of cocaine). In 2009, it seized 7.1 metric tons, five times the 2010 amount, according to the U.S. State Department. “Weak law enforcement and criminal justice institutions operate in an environment of pervasive corruption,” the State Department’s report read.

Michael Deibert agrees. As a visiting fellow at Coventry University's Centre for Peace and Reconciliation Studies he has studied security in Guatemala. “The problem is that the Mexican criminals sensed a perfect condition with which to operate with Guatemalan criminals,” he said.

The Peten, where the cattle ranch massacre took place, is a prime example. Guatemala’s northernmost department, which shares a porous border with Mexico, was once the cradle of Maya civilization. Their temples still haunt but in recent years the Peten has become better known as one of the most lawless regions in a country that only solves 2 percent of murders.

For years, Guatemalan drug traffickers have established operations under the nose of the government, knocking down mahogany and ceiba trees in supposedly protected national parks, building illicit landing strips for drug-laden airplanes and doing so with impunity, security experts and people who live in the area told GlobalPost.

(Read: How drug traffickers are taking over in Peten)

“Saying Mexicans have overrun the [border] area is an excuse for the government … so that it doesn’t have to deal with the real problem that is here,” said Sandino Asturias, founder of the Guatemala City-based Center for Guatemalan Studies and grandson of Nobel Prize-winning writer Miguel Angel Asturias. “The presence has been here for years and it’s controlled by local families. They’ve grown stronger due to the weakness of the state.”

For years, drug traffickers have been buying land from peasants in the area to establish enormous cattle ranches from which they could run drug operations. A 2010 study by the German Development Service of 236 municipalities in the department found that 30 percent of peasant farmers had sold their land in recent years.

In southeastern Peten, eight landowners possess 2,500 acres or more. Five of them, including the two largest landowners in the area, are known drug traffickers, the study found.

One of the other largest landowners in the region is the Guatemalan Ministry of Defense, which runs a military school to train Kaibiles.

“The drug cartels are made up of Guatemalans who are guided by the cartels, such as the Zetas and the Gulf. Many of the low-ranking [cartel] officers were trained in the same military school that is located in Poptun, Peten,” said a government official in the area who requested anonymity for fear of their family’s safety.

The official explained that many of those cartel members had been discharged from the military and found a well-paying job with the cartels. They “follow orders, kill, use military strategies to persuade people,” the official said.

Beltran said the government looked the other way while drug traffickers expanded their reach in the region.

“The land titles in many cases were in the names of known drug traffickers,” she said. “At the very least, there was acquiescence on the part of the government.”

Colom responded to the massacre by ordering a state of siege in the department. It allows security forces wide-ranging power to detain people on suspicion of involvement in organized crime.

Its effectiveness remains in question. Earlier this year, Colom declared a 30-day state of emergency for a neighboring department, Alta Verapaz. It was portrayed as a major government strike against Mexican cartels.

By the time it ended in February, more than 140 people had been arrested. However, by mid-May the last three of those suspects had been released from jail largely due to a lack of evidence against them, an official in the country’s Ministry of the Interior told GlobalPost.

“What that says is that the state of siege, the operations the government undertakes are all just a show,” Asturias said. “There is no real intelligence carried out in advance. The motive is to receive the publicity to make it seem as if the government is doing something about the problem. The fact is, the problem is just getting worse.”