ZITACUARO, Mexico - Back when President Felipe Calder�n first dispatched army troops to quell drug violence in December 2006, Mexico's criminal landscape was fairly clear: There were four main cartels, each with its own turf, and they fought mostly among themselves.

But nearly three years into the crackdown, new armed groups are springing up as the heightened attention has forced old cartels to splinter and evolve. The nascent cartels are ruthless, skilled in military tactics, adept at psychological warfare and eager to expand beyond drug smuggling into other criminal enterprises including extortion, kidnappings for ransom and even software piracy.

"Instead of wiping out organized crime, they've just made it more fragmented," said Guillermo Zepeda, a criminal-justice professor at the Western Institute of Technology and Advanced Studies in Guadalajara.

The most dangerous, according to the Mexican government, is La Familia Michoacana, which has flourished in the very place the crackdown began, the central state of Michoacan. But other new threats are rising fast: the Beltran Leyva gang, the Zetas, the Negros and Pelones, the Lynxes and a host of regional gangs.

The tenacity of organized crime in Mexico bodes badly for the United States, which is about to step up its involvement by sending police trainers, helicopters and $1.4 billion to help with the fight against drugs, said Ren� Jim�nez Ornelas, a crime expert at the National Autonomous University of Mexico.

"I look at Iraq and its consequences for the United States, and I see a similar black hole forming around this (anti-drug) strategy," Jim�nez said. "It's not producing results."

Evolving enemy

Three years ago, there were four main gangs supplying the United States with cocaine, heroin, methamphetamine and marijuana.

The Tijuana Cartel, also known as the Arellano-Felix Gang, controlled the California corridor. The Sinaloa Cartel, also known as the Pacific Cartel, grew marijuana and opium poppies, the raw ingredient of heroin. It also controlled routes through the deserts of Sonora and Arizona.

The Ju�rez Cartel handled routes through western Texas, and the Gulf Cartel operated along Mexico's east coast. The Sinaloa and Ju�rez cartels were allies.

The geographic divisions kept violence mostly in check, according to a report in May by the U.S. Congressional Research Service.

Any killings were mostly between drug dealers. Ajustes de cuenta, or account settling, was usually low-key: Someone just disappeared, never to be seen again. Running gunbattles in the streets were bad for business. Decapitations were nearly unheard of.

But the government crackdown has forced a reorganization. The Tijuana gang has been weakened by the arrests and killings of its leaders. The Gulf Cartel now picks up cocaine shipments on the Pacific Coast. The alliance between the Sinaloa and Ju�rez cartels collapsed in 2008.

"What was once a bi- polar competition between the powerful Gulf Cartel and the Sinaloa federation has been transformed by the government's anti-crime initiatives into significant inter-cartel and intra-cartel violence," the Congressional Research Service report said.

Increased security along the border means the gangs are now fighting over narrower and narrower corridors through the wilderness. The gangs control these plazas, or areas of influence, by sowing terror with gruesome acts that increasingly involve civilians.

Drug-related murders rose from 2,275 in 2007 to 5,207 in 2008, according to an unofficial tally by the Reforma newspaper. The 2009 toll stood at 3,757 as of Aug. 17. Of those, 104 victims had been decapitated, and 306 showed signs of torture.

U.S. assesses threat

The splintering of the cartels has led to violence bordering on terrorism, the U.S. State Department says. This month, it warned American travelers to avoid travel to parts of Michoacan and Chihuahua states as more civilians get caught in the bloodshed.

"Criminal gangs are now often in the control of more erratic and violent subordinates, leading to more killings and less predictable behavior," the department said in its 2009 report on drug strategy. "Trafficking organizations have also been effective at utilizing violence as a psychological weapon, intimidating political leaders, rival groups, and the general public."

On April 15, President Barack Obama added La Familia and the Zetas, a crime syndicate that recently broke away from the Gulf Cartel, to the U.S. list of international drug-trafficking organizations.

Moving in

La Familia Michoacana is the most brazen of the new groups, actively stalking and killing police and soldiers, the Mexican government says.

"The Familia Michoacana cartel is characterized by its virulence," Monte Alejandro Rubido, an adviser on Calder�n's National Security Council, told reporters last month. "It is, we believe, the cartel that combats authorities with the most belligerence."

La Familia's many side activities have allowed it to flourish even as drug smuggling gets harder because of increased U.S. border security.

The group's arrival in Zitacuaro, a city of 79,000 in Michoacan, was typical of the gang's modus operandi, Zepeda said.

First, it took over drug peddling. Then it began demanding protection money from bars and nightclubs. Then it moved to counterfeiting of DVDs.

Soon bodies were showing up with increasingly regularity in the ravine under the old iron bridge, a local landmark. A pair of severed heads appeared outside a car dealership. On July 3, police acting on an anonymous tip found four bodies buried behind a house outside Zitacuaro and another body dressed in military fatigues upstairs.

The violence has stunned Zitacuaro. The city 70 miles west of Mexico City is known mainly as a destination for migrating monarch butterflies.

"We used to be famous for butterflies. Now we're famous for murder," said Rafael Arriaga, an 84-year-old retired carpenter.

Federal prosecutors say La Familia also has moved quickly to corrupt politicians. On May 26, federal agents arrested 10 Michoacan mayors, including Zitacuaro Mayor Juan Antonio Ixtlahuac, on charges of protecting the group.

Terrorist attacks

On July 11 and 12, the gang showed the extent of its power, launching 15 coordinated attacks on police stations and officers in eight cities across three states, including an assault in Zitacuaro. In the worst attack, gunmen hijacked a bus carrying 12 federal police officers and killed them all.

The attacks followed the arrest of one of La Familia's leaders, Arnoldo Rueda Medina.

A recording taken by a traffic camera in Zitacuaro showed the speed and military precision of these attacks.

The gunmen arrive outside the city's federal police station in two sport-utility vehicles, hurl a hand grenade at the building, and then crouch in the street, raking the building with combat rifles and grenade launchers for exactly 90 seconds.

The gunmen then box in a stray police cruiser and shower it with bullets, killing the three officers inside, before driving away.

The entire attack took two minutes and represented perhaps the most well-coordinated cartel strike in a country that has seen its share of spectacular gang shootouts.

To stamp out La Familia and the rest of the multiplying cartels, Mexico's Public Safety Secretariat is building a network of regional command centers for the federal police. The aim is to be able to reach any point in Mexico by helicopter within minutes, the government says.

But much of the blame for the current anarchy lies with local police and prosecutors, not federal authorities, said Zepeda, the criminal-justice professor.

Local police have a better idea of who the drug traffickers are, where the drugs are moved and even where the bad guys may live. But they are either corrupt, scared to act or in over their heads, said Elena Azaola, an expert on crime at Mexico's Center for Research and Advanced Studies in Social Anthropology.

"They're not investigating these killings, finding out who are the responsible people and what is the reason," Azaola said.

The Mexican government says it is working to professionalize the police forces. The U.S. aid package has earmarked millions of dollars for forensic laboratories, satellite communications gear and computer systems to help prosecutors assemble court cases.

The government also says it is trying to purge corrupt local police officers. But it is targeting federal agencies first. On Aug. 15, for example, it fired all 700 customs inspectors at Mexico's airports and border crossings and replaced them with better-educated agents who had undergone psychological and criminal background checks.

Some recent arrests

The government also has chalked up some recent victories with the arrest of suspected La Familia leaders Rueda on July 5 and Miguel Angel "The Truck" Beraza Villa on Aug. 2.

On Aug. 23, the army said it had arrested Luis Ricardo Magana on charges of being the main coordinator for La Familia's methamphetamine shipments to the United States.

Calder�n has urged Mexicans to be patient.

"The final victory in a problem so big, with roots so deep, with trunks so aged and rooted in the life of the country, cultivated over years and decades, may take a long time," he said in a speech on Aug. 7.

But many Mexicans are starting to wonder if they'll ever be rid of the drug gangs.

"There's no work here, and so people turn to crime," said Maria Guadalupe Rodriguez, a 53-year-old shoe-shiner in Zitacuaro's main plaza. "You get rid of one group, and another just pops up."

Reporter Sergio Solache contributed to this article. Reach the reporter at chris.hawley@arizonarepublic.com