MEXICO'S VIOLENT DRUG CARTELS FINALLY MAY HAVE GONE TOO FAR

Two years and 2,500 killings into the raging drug cartel war, a
triggerman finally may have shot the wrong guy: Marcelo Garza y Garza,
a respected cop and key Mexican ally of U.S. law enforcement. Until
Tuesday, Garza, 36, had been the only chief of Nuevo Leon state's
organized crime investigations division.

He worked closely with the U.S. war on drug gangs and, unlike many
police officers executed by the cartels, he doesn't appear -- so far
- -- to have had illicit links to the bad guys he loved to throw in jail.

"Marcelo was by far our closest collaborator and most trusted
confidant," a senior U.S. official said on condition of anonymity.

"We have no reason to believe that Marcelo was involved in one camp or
another," said the official, referring to Mexican drug cartels that
routinely co-opt cops.

Garza was shot four times in the back of the head, shocking Monterrey,
a city fast becoming a battleground in the cartel turf war. Some
business leaders and state officials have routinely downplayed the
violence here.

Not anymore.

"This is no longer ... a war between (cartels) and executions between
them," said Gov. Natividad Gonzalez Paras. "They have now put
government functionaries in their sights."

State authorities appear in a paralytic shock over Garza's execution.
Officials reinforced their personal security and refused to discuss
details of the killing with the media.

Federal police reinforcements arrived in the state and police
checkpoints appeared on major thoroughfares.

Many fear Garza's killing heralds a new chapter in Mexico's drug war,
one perhaps similar to the drug cartel offensive against the Colombian
government in the 1990s.

The police chief in San Pedro, a rich Monterrey suburb, was killed
this February.

Last year, the police chief of Nuevo Laredo was shot dead just hours
after taking office. At least one high-ranking official in Michoacan
state was killed, apparently in revenge for jailing
traffickers.

There was an unwritten rule that high-level officials were off-limits
to drug-related killings, said one Nuevo Leon state official on
condition of anonymity.

"There was a line," said the official. "And they crossed
it."

Monterrey battleground

It's no secret that Mexico's rich northern city long has been a
playground for drug traffickers. Monterrey is prosperous enough to
make illicit money appear legal and has plenty of top schools and
upper-class neighborhoods.

The urban legend here is that enemy traffickers would ignore each
other if they met in the street, or even wave hello, in an effort to
keep the city safe for their families.

But more narcotics than ever are flowing through Mexico and the
struggle to control supply to the multibillion-dollar U.S. drug market
has broken the old truces. Gunmen are young -- many of them are former
police officers -- and every killing begs for revenge, officials said.

"All the groups here have virtual armies," said the senior U.S.
official. "The old rules don't matter anymore."

The newspaper El Norte, which keeps an unofficial tally, counted more
than 2,500 executions across Mexico in 2005 and 2006. Garza's
execution was the 36th of the year for Nuevo Leon, according to the
newspaper.

That's a record for the state but is considerably less than
neighboring Tamaulipas state, where a war to control the Nuevo
Laredo-San Antonio drug shipping corridor has claimed at least 300
people in the past two years, according to El Norte.

The spread of violence to Monterrey probably is part of that war. The
feared Zetas -- elite army defectors working for the Gulf Cartel --
are believed to be regaining the upper hand in Nuevo Laredo.

The Sinaloa Cartel, headed by fugitive drug lord Joaquin "El Chapo"
Guzman, is believed to be trying to wrest control of the corridor.

"Monterrey has always been a stronghold for the Chapo Guzman
organization, and Monterrey is very important because it is a
distribution ring," said a U.S. federal investigator on condition of
anonymity. "It's always been a sanctuary where not much goes on, but
now the violence has increased because the Zetas are increasing in
numbers."

Garza was shot with a Belgian-made Five-seveN pistol, which can fire
armor-piercing bullets and is restricted to army and police use in
Mexico.

Gov. Gonzalez denied repeatedly that Garza had been threatened, but
local media reported the contrary. Garza probably had plenty of enemies.

The day he was killed, the officer discussed with reporters the
seizure of a cache of automatic weapons and more than 1,000 rounds of
ammunition. He also announced a shake-up of Attorney General's Office
personnel, due to lack of confidence in some officials.

El Norte reported Garza had been threatened after leading the arrest
last year of a heavily armed team of alleged cartel triggermen, most
of them former police officers.

Scared people, business

Monterrey residents still live in one of the safest cities in Latin
America. Even the rich neighborhoods lack the high walls, electric
fences and razor wire common in Guadalajara or Mexico City's wealthy
suburbs. But the violence, which has included daylight shootings in
public places and kidnappings in front of police officers, has
residents rethinking their safety.

"When I see a Hummer with tinted windows, I get out of the way," said
a Monterrey resident who declined to be named. "This is scaring people."

Executives of U.S. companies in Mexico are taking measures to increase
personal security and potential investors are adding security
considerations into their business plans, said Roberto Cavazos,
executive director of the American Chamber in Monterrey.

"Obviously this is affecting investment," he said. "(Security) was not
an element that we had to consider in this part of Mexico."

Cavazos said Monterrey's influential private sector would not allow
the government to let the turf war spin out of control.

"It's our turf, too," he said.

Gov. Gonzalez said Mexican governors would present a plan next week
for combating organized crime at a federal level. But corruption, weak
governance and Mexico's uncoordinated municipal, state and federal
policing arms complicate effective crime fighting.

Arturo Arango, a Mexico City-based crime specialist, said spurious
operations, arbitrary arrests and stricter laws have not improved
security in Mexico. He said president-elect Felipe Calderon's proposal
to create a nationalized crime database and a federalized police force
is the necessary first step.

"Until we don't have a single system," he said. "It would be better to
do nothing."

Mariano Castillo of the Express-News Border Bureau in Laredo
contributed to this report.