The son of the acting head of Mexico's Sinaloa drug cartel has been cooperating with U.S. authorities as part of a plea bargain reached a year ago, federal prosecutors said here Thursday.

Jesus Vicente Zambada Niebla pleaded guilty in April 2013 to one count of conspiracy to distribute tons of cocaine and heroin in the United States, according to a documented presented in the U.S. District Court for the Northern District of Illinois.

The length of Zambada Niebla's eventual prison term will depend on his level of cooperation, but he has already agreed to forfeit more than $1 billion.

His father, Ismael "El Mayo" Zambada, remains at large and has been running the Sinaloa cartel since the recent arrest in Mexico of top boss Joaquin "El Chapo" Guzman.

Both Guzman and the elder Zambada are co-defendants in the Chicago case.

Zambada Niebla was arrested in the Mexican capital and extradited to the United States in February 2010. He admits to having coordinated the logistics for drug shipments and describes himself as a "trusted lieutenant" of his father. EFE