How 34 commandos created Mexico's most brutal drug cartel

The leader of Mexico's most brutal drug cartel was arrested early Wednesday morning, but his capture will likely have only a minor impact on what the US government has called "the most technologically advanced, sophisticated and dangerous cartel operating in Mexico."

With a strong presence in about 17 Mexican states - or half the country - Los Zetas is currently the largest criminal syndicate operating in Mexico.

Here's how the Zetas were developed:

The group started out as the enforcement branch of the Mexican Gulf Cartel. Originally comprised of 34 Mexican Special Forces soldiers, the death squad was tasked with protecting a young, upcoming leader of the Gulf Cartel, Osiel Cárdenas Guillén.

The Gulf Cartel was in the midst of a violent turf war when Cárdenas Guillén took over as its leader in 1999. For his protection, Cárdenas Guillén hired a bodyguard (retired Army lieutenant Ruben 'el Chato' Salinas), who then solicited 30 Mexican army deserters to form the cartel's well-paid mercenary wing.

Over the years, Cardenas expanded the Zetas' responsibilities. The group bribed and threatened their way to uncontested power until the Gulf Cartel became virtually untouchable by law enforcement.

By 2003, Los Zetas had expanded to include roughly 300 paramilitary men with sophisticated weapons and advanced military training. The Mexican Defense Department recognized the group as "the most formidable death squad to have worked for organized crime in Mexican history."

After a shootout with the Mexican military in 2003, Cárdenas Guillén was arrested and sentenced to 25 years in prison. By then, Los Zetas had far surpassed the Gulf Cartel in revenue, membership, and influence. In 2010, the Zetas broke away from the Gulf Cartel after years of internal conflict.

It did not take long for the cartels to become rivals and turn their weapons against each other. In attempts to intimidate the competition and recruit more members, the Zetas have carried out multiple massacres and attacks on civilians.

Between 2010-2011, the Zetas murdered over 350 farmers and migrant workers in Mexico and Guatemala who refused to join their ranks.

Ex-troops from Guatemala - counterinsurgancy experts known as "killing machines" - have been recruited by Los Zetas, and the cartel has set up camps around Mexico to train recruits aged 15 to 18 years old.

Most of the original 34 Zetas have been either captured or killed by Mexican authorities, but hundreds of hardened Zetas remain. The group has maintained its stronghold over 17 Mexican states, or half the country, and is also active in Texas.

The group continues to pose a threat to citizens on both sides of the border. The FBI believes that Los Zetas controls several U.S.-based gangs such as the Mexican Mafia, the Texas Syndicate, the Hermanos Pistoleros Latinos, and MS-13.

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