SAN DIEGO (AP) — The brother of a Sinaloa cartel leader has been arrested at an Arizona border crossing, less than a month after his nephew surrendered to U.S. authorities.

Federal prosecutors say 38-year-old Alvaro Lopez Nunez was taken into custody Thursday in Nogales, Arizona. He is being moved to San Diego to face drug charges with the kingpin's son, who turned himself in to border inspectors in Calexico, California.

They are related to Damaso Lopez Nunez, who has been battling for control of the Mexican cartel since last year's arrest of longtime leader Joaquin "El Chapo" Guzman. Known by the nickname "El Licenciado," a title for college graduates, Lopez was long considered Guzman's right-hand man. Mexican authorities arrested him in May, and U.S. authorities are seeking his extradition.