TIJUANA – The execution of 13 patients in a drug-treatment center in October challenged the often-repeated claim by authorities that such shocking crimes were declining.

Such rhetoric aside, the number of murders in the city for the just concluded year reached 818, just 25 shy of the record set in 2008.

In the first two months of 2010 police captured two of the local leaders of the bloody cell backed by the Sinaloa cartel, Teodoro García Simental, alias El Teo, and Raydel López Uriarte, alias El Muletas.

Subsequently, authorities from all three levels of government, as well as business leaders, began to publicly assert that the level of violence was decreasing.

At a high-tech conference in October, even President Felipe Calderón joined the chorus. In an appearance in the city, he said Tijuana was an example for the rest of the country because of its success in fighting organized crime.

Most of the violent deaths in 2010 were among lower-level dealers fighting each other for control of drug sales on the streets, according to state and local police authorities.

That's a departure from the previous two years, when the criminal cell headed by García Simental and López Uriarte tried to muscle out the Tijuana cartel, led by Fernando Sánchez Arellano, alias El Ingeniero, the nephew of Benjamín and Ramón Arellano, founders of that criminal organization.

That war resulted in hundreds of executions, many using sadistic methods not seen here before. And it also resulted in the disappearance of at least 390 people from 2008 to 2010, according an organization of family members seeking information about their missing loved one.

The execution of 13 residents at the drug rehabilitation center El Camino on Oct. 24 in an eastside neighborhood served unequivocal notice that criminals still could wage large-scale attacks.

According to the state Attorney General's Office, three gunmen gathered the residents in one room, ordered them to lay face down, and then opened fire with R-15 and AK-47 rifles.

No one has yet been arrested for these murders nor have authorities said what group may be responsible. The state agency believes that at least one other person participated in the crime, a man who drove the sedan the assassins used to get away.

A week before the massacre, authorities had seized 134 tons of marijuana, the largest seizure ever in Mexico. The marijuana was torched two days later in at the army base, drawing unprecedented national and international media coverage.

The images of the burning bundles were accompanied by phrases such as "historic seizure" or "crushing blow against organized crime."

Around the same time, the decapitated bodies of three men were found hung by their legs on bridges on the south and west sides, and there were several murders which bore the signs of having been carried out by organized crime.

Public officials, however, maintained that the city was safer and that roving groups of men were no longer carrying out attacks and kidnappings with impunity.

Victor Clark, a social anthropologist, said violent crime had indeed decreased in wealthy neighborhoods, downtown and in the city's financial center, the Río zone.

The social class who lives and works there felt more at ease, he said.

But people who live in the city's eastern area, where an estimated 1million of the city's 1.6 million residents live, never experienced a drop in violent crime, he said. Every day they received news of people who had been killed or had disappeared.

Clark said that the murder of the 13 patients at the rehabilitation center could make these facilities the new local battleground for the drug cartels who, like volcanoes, have calm periods while they reorganize and try to get more powerful weapons, and then erupt, leaving a trail of death.

Some drug-treatment clinics are used by drug dealers to hide there. They are rarely inspected by health authorities or raided, Clark said.

The official most known for taking on drug traffickers, Julián Leyzaola, no longer leads the Tijuana's public safety department. The new mayor, Carlos Bustamante, appointed someone else to this pivotal post last month.

Leyzaola, a lieutenant coronel retired from the Mexican Army, had carried out an unprecedented purge of the department: More than 600 officers suspected of being corrupt or of working with organized crime resigned or were expelled -- 84 of them were arrested.

But he was accused of torture by the state's Office of Human Rights, a case that has yet to be resolved.

Even so, Baja California Gov. José Guadalupe Osuna appointed him the state's deputy director for security.

Tijuana's new public safety chief is a captain also retired from the army, Gustavo Huerta, who headed the municipal police department under Leyzaola.

On the next to the last day of 2010, five young men were shot to death in various locations in the city. Regardless of public pronouncements to the contrary, Huerta is inheriting a department which will have to confront this level of violence.

Omar.millan@sandiegored.com