The mayor of this well-groomed town in central Mexico, Vergara traveled without bodyguards even after callers to his cellphone tried to extort $70,000 from him, and demanded that he play ball with drug traffickers, friends said.
"He didn't give them what they wanted," said Raymundo Fuentes, a city councilman. "What happened was bound to happen."
On Oct. 4, Vergara was ambushed on a rural highway near here as he returned from a visit to neighboring Guerrero state. Gunmen in six cars besieged the white Chevrolet Trailblazer and opened fire with AK-47s and shotguns. When the SUV came to a stop, the attackers poked the barrels inside and fired some more.
Vergara died. Fuentes and a third city official in the car were wounded, but survived. "Only God knows why," said Fuentes, whose right wrist is lumpy with shotgun pellets still buried in his flesh.
Vergara, 34, a member of the once-ruling Institutional Revolutionary Party, or PRI, is among at least 11 Mexican mayors and ex-mayors who have been killed or have disappeared during the last 15 months. Many more have received extortion demands. Others, such as Jose Reyes Ferriz, the mayor of beleaguered Ciudad Juarez, received public death threats.
Mexico's 2,400 mayors occupy a dicey spot on the front line of the country's war on drug traffickers. They are prime targets for bribe offers because they oversee local police. And well-meaning mayors are hard pressed: Most municipal governments have skimpy tax bases from which to equip and pay police well enough to break long-standing graft.
Mayors complain that they are the ones who personally confront the toll of drug violence on the streets. Yet they lack any meaningful role in the federal government's battle against organized crime -- municipal police, by law, are restricted to petty crime and traffic offenses.
"They're in the hottest seat," said George Grayson, a Mexico scholar at the College of William & Mary in Williamsburg, Va. "The mayors are really in the most precarious position."
The most endangered mayors govern towns along drug-smuggling routes. In February, gunmen killed the mayor of tiny Vista Hermosa, in the western state of Michoacan, a hotly contested trafficking corridor. Two weeks earlier, the mayor of Otaez, in the state of Durango, turned up wrapped in a blanket.
The nation's rising death toll, which exceeds 7,600 since January 2008, also includes council members and other municipal staffers.
The intensifying violence aimed at City Hall has instilled fear. The mayor of Petatlan, in a section of coastal Guerrero state bedeviled by drug violence, sought to avert trouble by announcing that his cops would have nothing to do with arresting traffickers.
The conservative National Action Party of Mexican President Felipe Calderon had difficulty fielding mayoral candidates in the northern state of Nuevo Leon this winter. The party's state director said potential candidates feared the growing crime wave, though the PAN's national leadership denied that was the reason.
Analysts say the rise in violence at the municipal level reflects political changes in Mexico, where the former ruling party, the PRI, has ceded the top-to-bottom control it once wielded, including over the drug trade.
Under PRI mayors, governors and presidents, traffickers largely went about their business with little trouble as long as they kept killings down and maintained payoffs to the right politicians.
But the rise of a multiparty system in Mexico during the last 20 years has upended that tacit pact.
Representatives of drug gangs, armed with campaign cash, often make overtures to political candidates. In return, they want a docile police department that will leave them to conduct their trade.
"What organized crime mainly asks from mayors is very simple: 'You see nothing,' " said Sergio Arredondo, who heads a federation in the PRI that represents municipalities. Mayors, he said, are caught "between the sword and the wall. . . . They're fighting against an enemy that's much better equipped, much better financed."
Under Mexican law, authority for policing and prosecuting drug-trafficking crimes rests with the federal government. State police handle other major crimes, such as kidnapping and murder, whereas municipal officers are left primarily with a preventive role.