The arrest in Southern Mexico this week of a leader in the Zetas cartelwill likely be followed by violent reprisals, "which almost always occur after a big shot is captured," an expert warned.

"The Zetas are the most sadistic, brutal cartel in Mexico. They're the ones who enjoy decapitating people, tossing them in vats of acid, dismembering them before they kill them," said George Grayson, a Mexico expert at the College of William & Mary in Virginia and author of a book published last year on the rise of narco-violence in Mexico.

"Some of the cartels do public works to try to develop bonds with the community. The Zetas are just the opposite. They want to terrorize communities," said Grayson, who is the author of "Mexico: Narco Violence and a Failed State?"

Mexican federal police on Monday announced the arrest of Flavio Mendez Santiago, 35, nicknamed "El Amarillo" or the "yellow one," outside Oaxaca City. He was arrested with a man who was identified as his bodyguard.

Mendez Santiago is one of the founding members of the Zetas and was in charge of its operations in Oaxaca, Chiapas, Veracruz, Campeche and Quintana Roo. He's been accused of homicide, drug and human trafficking and kidnappings.

The Zetas are linked to the massacre of 72 Central and South Americans, whose bodies were found in August in the northern Mexican state of Tamaulipas, not far from the Texas border. Mendez Santiago is believed to have been in charge of smuggling undocumented immigrants from Central and South America.

In September of 2009, the U.S. Department of Homeland Security said that the Zetas planned to kill law enforcement officers in Arizona, New Mexico andTexas.

And last summer, officials with the Los Angeles Police Department warned that Zeta members were recruiting ex-convicts released in Southern California and taking them to Mexico to train them to work for the cartel.

The Zetas were formed in the late 1990s by renegade Mexican soldiers and originally operated as private mercenary army for Mexico's Gulf Cartel. The Zetas transitioned to be their own cartel and are now enemies of their former bosses.

Los Zetas' aggressive methods have been copied by other drug cartels in Mexico.

"Some of the cartels that did not practice this excruciating terror have now become more violent," Grayson said.

While the Mexican government has won praise for declaring war on drug traffickers, it lacks the ability to take down major criminal organizations in one swoop, Grayson said.

"The Mexican government follows the trophy policy. They want lots of capos captured so they can put trophies on a wall," Grayson said. "What it has not done is undertake a sweep of 20 or 30 Zetas. They need to make multiple arrests at the same time. This is what U.S. authorities have done in the United States against La Familia. They hit them across the country," Grayson said referring to the apprehension of more than 300 people connected to the Michoacán-based drug cartel La Familia in September.

"The Mexican government doesn't have the ability to make simultaneous raids on a couple of dozen of Zeta members, which needs to be done."

The arrest of Mendez Santiagowill disrupt Zetas' operations, but their top two leaders. Heriberto Lazcano and Miguel Trevino, remain at large.

"The Zetas will now go out and there will be reprisals," Grayson said. "There will be more violence."

The Associated Press contributed to this report.