Mexico City ? Mexican authorities believe they have arrested the leader of the Juarez drug cartel and said Monday they were conducting tests to verify his identity.

If officials confirm that the detained man is in fact Vicente Carrillo Fuentes, it would be a rare glimmer of good news for Mexico’s anti-narcotics forces amid an explosion of violence this year.

Agents of Mexico’s Federal Agency of Investigation arrested the suspect at an upscale Mexico City shopping mall Saturday, said Ruben Aguilar, spokesman for President Vicente Fox.

Aguilar said prosecutors were conducting fingerprint and DNA tests to verify the identity of the man, who gave his name as Joaquin Romero Aparicio and who local media said had undergone extensive plastic surgery. Drug kingpins often use phony names and disguises to elude authorities.

“Right now, it’s presumed that this is Vicente Carrillo, but it’s not completely confirmed,” Aguilar said.

Carrillo’s brother Amado, once considered the most powerful drug lord in Mexico, is believed to have died in 1997 during a botched plastic surgery to change his appearance. Experts said capturing Vicente Carrillo would deal another blow to a drug gang that has lost influence and cohesion since Amado’s death. Another Carrillo brother, Rodolfo, 29, was killed in a shootout with rival gangs in Sinaloa state in September.

“If it’s true, it’s a big deal because it puts a dent in their organizational structure,” said Rene Salinas, an FBI special agent in San Antonio.

The arrest of Carrillo would be a major boost for Fox, who has been under pressure from the United States to stem a tide of drug-related violence that has claimed more than 600 lives this year, many along the border. Bodies are turning up almost daily from Tijuana to Cancun, many of them bearing marks of torture and mutilation that are the calling cards of organized crime.

Fox has vowed the “mother of all battles” against narcotics traffickers, with 18 top leaders toppled during his administration. While veteran observers call that record impressive, they say it has done nothing to restrict the flow of drugs into the United States and has ratcheted up tension among gangsters.

For example, authorities trace a recent spasm of violence in the border town of Nuevo Laredo to the 2003 arrest of Osiel Cardenas, the alleged leader of the Gulf cartel. Sensing the opportunity to take control of a new smuggling route to the United States, his rivals, led by Sinaloa-based Joaquin “El Chapo” Guzman, moved in, setting off a bloody turf war.

Jorge Chabat, a Mexico City political scientist and an expert on organized crime, said that while the United States would welcome the capture of Carrillo, his arrest could paradoxically provoke even more killing as aspiring kingpins scramble to take his place.

“It won’t make any difference in the flow of drugs,” Chabat said. “And we’re probably going to see more violence.”

The Juarez cartel, which takes its name from the border city of Cuidad Juarez, flourished in the 1990s under the leadership of Amado Carrillo. Nicknamed the “Lord of the Skies,” he became a legend by ditching the small boats and prop planes of his predecessors, instead ferrying cocaine by the ton from South America in large jets.

But his death is believed to have loosened the confederation of traffickers that once formed the core of the cartel. The killing and jailing of drug leaders throughout Mexico has destabilized rival drug gangs as well, to the point where no one cartel predominates.

U.S. drug enforcement sources say that as many as 13 Mexican crime groups are battling to control the lucrative drug trade, forming alliances that are constantly shifting.