Two weeks ago an enraged mob swarmed three federal police officers in the Mexico City suburb of San Juan Ixtayopan, beat them nearly lifeless then burned two of them alive while thousands watched live on national television. The locals who committed the crimes thought the victims were kidnappers. The incident, which received global press coverage, was deeply embarrassing to Mexican government officials, who were still in damage-control mode last week. Mexicans themselves continued to grapple with the social implications of the crime. Authorities moved quickly to arrest 29 people, some of whom had been caught by the TV cameras pouring gasoline on the police officers or, in one case, apparently touching a lighter to the gasoline-soaked victims. President Vicente Fox fired Mexico City's chief of security, Marcelo Ebrard, for mishandling the crisis, but not before tersely announcing a "zero tolerance" policy toward what many fear is a rising tide of vigilantism in the country. "My government will not permit these savage acts [that] put our society in danger," Fox told reporters.

Dramatic as it was, the cop killings were not an isolated incident. Vigilantism has taken root in Latin America over the past decade, lending credence to the notion that the region is in the throes of a democratic crisis. From Venezuela and Guatemala to Bolivia and Peru, angry crowds are increasingly taking the law into their own hands, meting out physical punishment for crimes real and imagined. Vigilantes often "lynch" common criminals who, in their view, have escaped justice. More recently they've started attacking public officials suspected of malfeasance. Last May a mob in the Peruvian town of Ilave beat their mayor after accusing him of embezzlement, then dragged him into a public square and left him to die. "Lynching has grown totally out of control," says Mark Ungar, an expert on Latin American police reform at the Woodrow Wilson International School for Scholars in Washington. "It's spreading in the sense that vigilantes are going after criminals, officials, even governments--and once it starts it's hard to stop."

Mob justice has a long history in Latin America, reaching as far back as colonial times. The first victims were Indians and slaves who violated the social order, property or "honor" of their New World masters. Indigenous communities have long used societal coercion and public shaming to punish community members who breach customs. More recently, however, economic stagnation, unabated corruption and a growing dissatisfaction with democracy are leading the region down a more perilous path. The U.N. Mission to Guatemala documented 482 lynchings between 1996--when the civil war ended--and 2002. Nearly all were carried out in rural, otherwise low-crime areas and involved the public burning or hanging of thieves or drug dealers. Bolivia has seen an alarming rise in vigilante justice, centered in the Altiplano (highlands) region.

Experts generally agree that vigilantes are not merely filling a law-and-order gap created by poor or nonexistent police work. The phenomenon is more complex. The western highlands of Guatemala, where many incidents of lynching occur, is not an area with an otherwise high rate of official crime. Rather, vigilantism is most prevalent in places where people have lost faith in their civic institutions. They no longer trust the police or judicial officials to care about their duties or the people they've been entrusted to protect. Indeed, corrupt police are part and parcel of the problem. A neighborhood protection group in Honduras recently told Ungar that they pulled people out of their houses frequently "and beat the hell out of them"--often while the local police were watching. Says Ungar: "The local officers allowed it to happen."

Analysts say that many cases of vigilantism are desperate attempts by disenfranchised groups to assert a nascent political will. In one case, closely documented by University of Washington sociologist Angelina Godoy Snodgrass, thousands of people gathered on a farm in rural Guatemala in October 2001 to witness the hanging and burning of three men suspected of stealing some fertilizer and candy. In a recent article, Snodgrass notes ominously that the process was "clearly premeditated... [community] security committees had been constituted to handle crime." If vigilantism is left unchecked, say experts, the problem could develop into something even more sinister--swaths of Latin American territory where mobs and mafia types rule. Snodgrass believes the trend is part of the "dark side of democracy."

Bolivia has tried to implement eight different police-reform programs over the last five years, and all have failed spectacularly. Police there are regularly promoted for looking the other way at gross corruption. Mexico City officials paid a security-consulting group led by former New York City mayor Rudy Giuliani more than $4 million to advise them on the capital's crime problem. But according to Mexican democracy advocate Ernesto Lopez Portillo, the city has done little to implement a major Giuliani recommendation--that the Mexico City police force should develop a system of accountability and be subject to external review.

That explains why Mexicans are so deeply cynical about their law-enforcement agencies. A recent study found that more than 50 percent of Mexicans were willing to tolerate relatively minor police abuses if the cops could significantly reduce the crime rate. Last summer 250,000 Mexicans took to the streets to protest the violence that plagues the capital, including a dramatic rise in kidnappings. It's that disgust, say researchers, that has spawned the wave of vigilante justice. "A lot of people have [acknowledged] to me that they've participated in [vigilante acts]; and that, yes, they would do it again; and that yes, it was the most awful thing they ever saw," says Snodgrass. "People were conscious of the horror, but they felt their backs were to the wall."

Certainly, intense frustration was the issue in the case of the Mexican police officers who were murdered. The inhabitants of San Juan Ixtayopan, a poor neighborhood, expressed little remorse over the deaths even after it became clear that the victims were, in fact, police and not would-be criminals. Indeed such was the anger last week that residents claimed they wanted a decreased police presence on their streets after the incident. They claimed they would rely on their own community policing network to do the job--the same one that killed the policemen. When the seething crowd of San Juan Ixtayopan first snatched Victor Mireles, Cristobal Bonilla and Edgar Moreno out of the crowd last Nov. 23, it was because community sirens on local houses had gone off--makeshift alerts fashioned to warn residents of intruders. Now in the wake of the killings, many in Latin America might hear those sirens as something more symbolic--a sign of widespread discontent with a corrupt law-enforcement system, and a warning of worse times to come.