A nephew of captured Gulf Cartel boss Osiel Cardenas Guillen, who was hiding out in the US to avoid rivals in the group, has pleaded guilty to drug trafficking charges in a US district court.

Rafael Cardenas Vela, alias "El Junior," (see photo, left) acted as a plaza boss for the cartel, according to prosecutors, managing operations in the city of Matamoros, across the Rio Grande from Brownsville, Texas.

When he was arrested in 2011, Cardenas Vela was hiding out from a former Gulf associate in Texas, according to US prosecutors. He fled Mexico due to a dispute over who would take power after the death of Osiel Cardenas Guillen's brother, Antonio, alias "Tony Tormenta," in December 2010.

InSight Crime Analysis

The fact that Cardenas Vela was living in the US to escape his rivals while continuing his operations is unusual, as Mexican traffickers usually prefer to run things from the relative safety of their home country. His move to the US, which has far stronger law enforcement, suggests that he must have perceived the threat from his Gulf rivals as extremely serious.

InSight Crime recently reported on a similar case, in which a faction of the Tijuana Cartel (Arellano Felix Organization) based themselves in San Diego after splitting from the Tijuana bosses.

The arrest and trial of Cardenas Vela, and the fact that he was hiding out from internal strife in the US, point to the declining clout of the Gulf Cartel. Since they split from their enforcer arm the Zetas in 2010, their territory has been shrinking.

Cardenas Vela's uncle Osiel Cardenas Guillen was arrested in Mexico in 2003, extradited to the United States in 2007, and sentenced to 25 years in prison in 2010.