Mexico has initiated extradition proceedings against an alleged Zetas drug cartel member wanted on U.S. homicide charges in the killing of a U.S. immigration agent.
The Attorney General's Office said Tuesday that suspect Julian Zapata Espinoza is now being held on a U.S. extradition request.
That is just the beginning of an extradition process that is complex and could take years.
Zapata Espinoza is known by the nickname "El Piolin," or Tweety Bird.
He is a suspect in the Feb. 15 highway attack that killed U.S. Immigration and Customs Enforcement agent Jaime Zapata and wounded colleague Victor Avila.
Zapata Espinoza was arrested Feb. 23 with five other suspected Zetas at gang safe houses in the northern city of San Luis Potosi.