TIJUANA, Mexico, March 14 (Reuters) - A former boss of Mexico's Tijuana drug cartel freed from a U.S. jail last week after 15 years behind bars is coming home to a gang badly weakened by army raids and territorial gains by rivals.
The family-run Arellano Felix cartel has controlled smuggling routes around the border city of Tijuana for years, using gruesome torture and executions to hold onto its turf.
But as the clan's eldest brother Francisco Rafael Arellano Felix returns to Mexico from a U.S. prison, the cartel, now run by one of his sisters, has lost ground to its enemies.
"They've been cut down to size in many ways. They don't have the penetration they did," said Bruce Bagley, a University of Miami professor who studies Mexico's drug cartels.
President Felipe Calderon's army-led crackdown has rounded up traffickers and busted police protection rings, and the powerful Sinaloa cartel from western Mexico has muscled its way into the Arellano Felix gang's home turf.
Experts say some Tijuana smugglers are breaking away and teaming up with the Sinaloa cartel on some drug deals.
"We're seeing the emergence of a post-Tijuana cartel structure in which you have smaller organizations, splinter groups, some of whom have now allied themselves with the Sinaloa cartel in a kind of confederation-like arrangement because they need protection," said Bagley.
In another blow to the Arellano Felix cartel, one of its high-level operatives, Gustavo Rivera Martinez, was arrested this week and is being extradited to face drug charges in the United States.
Francisco Rafael Arellano Felix, released from a Texas prison last week, ran the Tijuana cartel at the peak of its power and opulence and was a fixture at flashy discos and restaurants in the seedy border city until his arrest in 1993.
Although sources say he is already back in his old stomping ground in the northwestern state of Baja California, analysts expect him to play a hands-off "godfather" role rather than take over the cartel's operations.
They say Enedina Arellano Felix, one of four sisters, is now managing the family business after other brothers were arrested or shot dead in a shootout with police.
Police say she handles its many organized crime and money laundering arms, but her grip on the cartel's prized smuggling routes has been shaken.
Last year, the Sinaloa cartel took control of Mexicali, a key smuggling city on the U.S. border that was formerly Tijuana cartel turf.
A mass of extra troops in Tijuana this year has also hurt, along with a new tip-off system that triggered half a dozen raids and put 30 mid-level Tijuana cartel operatives in jail.
Drug hitmen responded to the tip-offs by slaying informants and leaving messages with their bodies like: "Keep calling". They also shot dead two children during revenge attacks.
With corrupt police who protected them being weeded out, and tighter U.S. border security, traffickers have tried to talk security forces into leaving them alone if they tone down their violence, local army Gen. Sergio Aponte says.
"They are trying to negotiate because they are losing the battle and it's a desperate reaction," he told reporters.
Despite the reverses, the Arellano Felix cartel is still fighting to remain the dominant force in and around Tijuana, and few expect a decrease in the gangland killings.
Similar turf battles have erupted across large areas of Mexico, killing more than 2,500 people in 2007, but the violence and Calderon's offensive have not stopped the trafficking.
"Drugs keep crossing the border, and drug distribution is still going strong," said Victor Clark, a professor at the San Diego State University. (Additional reporting by Cyntia Barrera Diaz; Writing by Catherine Bremer; Editing by Kieran Murray)
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