Ismael "El Mayo" Zambada decided to stick with the lawyer defending him from U.S. drug trafficking charges despite a possible conflict of interest.

Zambada's lawyer Frank Perez has also represented his son, Vicente Zambada Niebla, who prosecutors say could testify against him at trial. Zambada Niebla previously testified against Joaquin "El Chapo" Guzman, who founded the notorious Sinaloa Cartel alongside Zambada.

The alleged cofounder of the Sinaloa Cartel, in U.S. custody since his arrival in July, could strike a deal to avoid the death penalty.