CIUDAD JUAREZ, Mexico (Reuters) - One man looms behind the worst violence in a drugs war on Mexico's U.S. border that is shaking President Felipe Calderon's government and worrying Washington.
Joaquin Guzman, known as "Shorty" at just 5 feet tall, is Mexico's most wanted man and set off a wave of killings in the border city of Ciudad Juarez early last year when he tried to muscle in on the territory of a local cartel.
A turf battle between Guzman's enforcers from the Sinaloa cartel and local Ciudad Juarez drug runners has since killed more than 2,000 people here and forced the government to deploy 7,500 troops and federal police to take control of the city.
Guzman, 51, has avoided capture several times since he escaped from a high security jail in a laundry van in 2001.
Mexican anti-drug officials say he began waging war for Ciudad Juarez when the local cartel tried to charge him taxes for smuggling narcotics through the city into Texas.
"Guzman has been pouring hitmen and resources into the city since last year to try to eliminate the Juarez cartel," said Tony Payan, a drug-trade analyst at the University of Texas in El Paso. "He has not been able to dislodge them," he added.
The killings have turned Ciudad Juarez into the most violent city in Mexico, where more than 6,000 people died in drug warfare last year.
Guzman, who officials believe changes his cell phone every day to avoid being tracked, is also fighting for control of the lucrative smuggling route through Tijuana into California, turning the city into one of Mexico's most bloody.
He set off a similar fight for smuggling routes into eastern Texas in 2006 but has so far been driven back by the rival Gulf cartel that has long controlled the area.
U.S. and Mexican authorities say Guzman has also been weakened by a break-up of factions within his cartel because of internal conflicts, and pressure by Mexico's military.
But he appears far from defeated.
"He is the silent shadow across Mexico. He is everywhere," said a senior Mexican military official in Ciudad Juarez who declined to be named.
Guzman is unlikely to be in Ciudad Juarez himself and state prosecutors say the hundreds of bodies that have come through the city's morgue are mainly cartel foot soldiers and police.
Guzman's prison escape and ability to elude capture for eight years is an embarrassment to the Mexican government.
He has outwitted four major government drives to find him between 2002 and 2007. His escapades are the stuff of legend in the areas he controls and in popular "narcocorrido" songs that glorify drug traffickers.
The closest call came when 100 elite troops were 10 minutes away from catching him in November 2004 at his ranch in Sinaloa before he escaped after a tip off.
"He's almost untouchable," said a senior U.S. anti-drugs official who declined to be named. "The moment we send a helicopter to anywhere near where we think he is, we are burned by informants."
When Guzman married his 18-year-old bride in 2007 at a wedding in the northern state of Durango, U.S. officials say they knew about the event but that the kingpin was too heavily guarded for Mexican soldiers to reach him.
Using a wide network of safe houses ranging from plush haciendas to caves, Guzman is at his safest within Mexico's so-called Golden Triangle, the mountainous, drug-producing region in the states of Sinaloa, Chihuahua and Durango, where he has bribed police to protect him, the government says.
Following an attempt to capture him in 2005, Mexico's deputy attorney general at the time, Jose Luis Santiago Vasconcelos, said Guzman was "one of the most intelligent men" authorities had ever faced.
Guzman learned the drug business in the 1980s as an associate of the so-called "godfather" of Mexican narcotics trafficking, Miguel Angel Felix Gallardo, who pioneered cocaine smuggling routes to the United States for Colombian cartels.
At the head of his own gang in the early 1990s, Guzman used tunnels to haul huge quantities of cocaine into Arizona and California from northern Mexico. In one seizure alone, police found 7.3 tonnes of the drugs in cans of chili peppers.
(Editing by Kieran Murray)