Suspect in general's murder arrives in Mexico
Luz del Carmen Solares de la Rosa's extradition was approved by Spain on Feb. 1.
Solares de la Rosa arrived in Mexico City aboard an Aeromexico flight at 8:22 p.m. Monday accompanied by three Attorney General's Office agents.
Television reports showed AG's office vans leaving the agency's hangar at the airport with Solares de la Rosa presumably inside.
The suspect was arrested by Spanish police in March 2012.
Solares de la Rosa allegedly hired the hitmen who killed the 65-year-old general, with whom she apparently had both a romantic and business relationship.
The woman has been linked to a company that supplies military uniforms, officials said.
Juarez Loera was gunned down on May 21, 2011, in Tlanepantla, a city in the central state of Mexico, which surrounds the Federal District and forms part of the Mexico City metropolitan area.
The recently retired general was attacked by three subjects who intentionally caused a traffic accident to get him to leave his vehicle.
Juarez Loera retired from the army on May 1, 2011, after holding a number of commands and achieving the rank of major general.
Media outlets reported that Juarez Loera was in charge of "Joint Operation Chihuahua" in 2008, commanding the military zone with jurisdiction over the northern states of Chihuahua, Durango and Coahuila.
The operation was a key part of former President Felipe Calderon's strategy of militarizing the war against Mexico's drug cartels.