A pair of recent arrests have underscored the increasing vulnerability of La Linea, once one of the most potent criminal groups in Juarez, Mexico's most notorious city.

The arrest in the Chihuahua city of Linea leader Marco Antonio Guzman earned international attention last week largely because of his flashy nickname -- "El Brad Pitt" -- but it was also a blow to a group that has suffered a number of setback over the past year. Days later, another heavyweight, Jose Guadalupe Rivas, alias “Zucaritas” or “Frosted Flakes,” was also arrested in Chihuahua, the capital of the state which which it shares a name.

While based in Juarez, La Linea also operates in Chihuahua city, which lies about four hours south of Juarez and serves as a staging area for drugs flowing northward, and other towns around the state.

In addition to these recent detentions at the top of La Linea’s hierarchy, the group has also suffered a number of arrests of larger groups of foot soldiers in recent months. In early June, eight members of the gang were arrested by the army in Praxedis G. Guerrero, Chihuahua, a border town of some 2,000 residents a short distance from Juarez. The army arrested three more in early April in Villa Ahumada, Chihuahua, which lies along the highway connecting Juarez and Chihuahua. In Juarez, the Federal Police arrested five alleged membes of La Linea on March 23, seven more on March 4, and two more on March 2.

While a larger organization might be able to absorb such losses from its ranks without much trouble, such sustained pressure for a group whose size and geographic scope are limited is much more damaging.

These arrests reflect what appears to be an ongoing decline of La Linea. While the gang has long been one of chaotic Juarez’s most fearsome groups, La Linea’s influence has declined over the past several months, and they no longer present the threat that they did in years past.

La Linea first emerged as a group of gunmen at the service of Vicente Carrillo’s Juarez Cartel. The group has been instrumental in helping Carrillo hold onto some semblance of territory in the city -- which is home both to one of the most important border crossings in Mexico and to a growing local retail drug market -- despite the incursion of the Sinaloa Cartel.

La Linea has been linked to some of the city’s most notorious crimes in recent years, including the massacre of more than a dozen partying teenagers in January 2010, and a car-bomb attack against the Federal Police in July of the same year. Both of these crimes earned a great deal of media attention, and placed the group in the crosshairs of Mexico’s security agencies. After the October arrest of Fernando Contreras, whom the government accuses of arranging the car bomb attack, Mexican officials began saying that La Linea was virtually dismantled.

The group’s decline coincides with a broader improvement in Juarez’s security. Despite holding the unofficial title of Mexico’s most dangerous city for the past three years, the number of murders in Juarez during May 2011 was the lowest in more than two years. While the government has offered few specifics with regard to explanations for the drop, the decline of one of the most violent protagonists has likely played a significant role.

In response to its decline, La Linea has sought an alliance with the Zetas. Because of their greater manpower and wider geographic reach, the Zetas offer La Linea the chance to stay relevant even as they take hits in Chihuahua. As with the recently arrested Famila boss Jose de Jesus Mendez Vargas, alias "El Chango," an alliance with the Zetas seems to have been a last resort for a waning group. For the Zetas, an alliance with La Linea could give them a toehold in the region, where they have never had a great deal of influence.