The 34-year-old Vergara was killed by hooded assassins armed with semiautomatic rifles as he drove with other officials toward his home city of Ixtapan de la Sal on Saturday afternoon.
The killing of a sitting elected official may turn out to be one of the more significant political slayings in Mexico's raging drug war, not so much because of who he was as for what his death represented.
Prosecutors in the state of Mexico say Vergara was killed because he refused to allow drug gangs to move into and operate freely in his city, along a transit route for drugs into the nation's capital.
Still, by Tuesday, Mexican authorities had arrested 14 suspects, including the mayor's former driver and two men named as the shooters. Some of the suspects, prosecutors say, claimed to be members of La Familia, a gang of drug runners and hit men based in neighboring Michoacan state. This would constitute further and especially forceful evidence of efforts by the gang to move into the state of Mexico, ever closer to the center of national authority.
Already, purported thugs from La Familia have been demanding payoffs from merchants in Ixtapan de la Sal to avoid having their businesses torched or their personnel attacked, according to local media accounts.
"Precisely because [Vergara] refused to have any contact whatsoever with people involved in the distribution of drugs, this attack occurred," said Alberto Bazbaz, attorney general for the state of Mexico.
More than 3,000 people have been killed across the nation this year as the government battles drug trafficking organizations and the gangs, at the same time, fight among themselves over territory and smuggling routes. The government of President Felipe Calderon launched a major crackdown on the drug organizations nearly two years ago, but violence has only intensified. The vast majority of the dead have been traffickers and members of government security forces; rarely has a sitting elected official been targeted.
The killing of Vergara may also have been intended as a message to Enrique Peña Nieto, the charismatic, high-profile governor of the state of Mexico and likely presidential candidate for the Institutional Revolutionary Party, or PRI. Vergara belonged to Peña Nieto's inner circle and had been tapped to run for a seat in the national Congress next year.
The mayor's slaying sent spasms of panic through the state's political leadership, with a dozen or so mayors saying they too had received death threats and were in dire need of protection. (One of them reportedly said he had already confessed to his priest to prepare for death.)
Peña Nieto, serving as a pallbearer at Vergara's funeral Sunday, pledged a blindaje, or security shield, for the officials. But several mayors were grousing Tuesday that they had received no additional protection.
"We will soon know what Enrique Peña Nieto is made of," commentator Francisco Garfias wrote in the Excelsior newspaper.
"He has the opportunity to show that he's got what it takes to aspire to the Big One in 2012," the year of the next presidential election.
"The challenge is immense."
Ixtapan de la Sal, about 55 miles southwest of Mexico City, is a popular resort known for its thermal springs and spas and a major getaway attraction for the residents of this sprawling capital. A month ago, 24 bodies were found at another popular tourist spot outside Mexico City, the La Marquesa park. Most of the victims were bound and had been shot in the head.
Principal transit point
German Garciamoreno Avila, head of the State Security Agency, said Ixtapan de la Sal had emerged in recent months as a principal transit point for drugs coming from the state of Guerrero to Mexico City.
It was that development that emboldened the traffickers and cost Vergara his life, Garciamoreno told the online version of El Universal newspaper Tuesday.
For many Mexicans, the killing of a mayor was one more drop in the lake, as the expression goes. After so many slayings -- the number this year already has surpassed that of all of last year -- the distinctions between who the victims are have become blurred. In a public opinion survey this week, Mexicans overwhelmingly listed drug trafficking and violence as the greatest threats to the nation.
"They will kill anyone who disturbs them, who refuses to collaborate with them, who threatens them," Sergio Aguayo, an analyst at the Colegio de Mexico, said of the drug gangs.
"The significance [of the mayor's slaying] is that they have decided to respond to the government's war on them with more war, and they are determined to continue."