Mexico said on Tuesday it would seek to void a court decision that freed a Mexican drug boss imprisoned for ordering the 1985 torture and murder of a U.S. drug enforcement agent, a ruling that has angered the United States.
A Mexican court on Friday cut short the 40-year sentence Rafael Caro Quintero was serving for orchestrating the killing of Drug Enforcement Administration agent Enrique "Kiki" Camarena, ending his 28-year stay behind bars.
It ruled that he should have been tried in a state court instead of a federal one.
The decision outraged the U.S. government, with some officials demanding Caro Quintero face charges in the United States for ordering the murder.
"We will have to look for legal avenues at the disposal of the Mexican state to nullify the decision this judge made," Mexican Foreign Minister Jose Antonio Meade told reporters.
Mexico's judiciary is independent of the executive branch, and it was not immediately clear what steps the government could take to have the decision overturned.
Caro Quintero, whose lawyer could not be reached for comment, was a leader of the Guadalajara cartel, a forerunner of the Sinaloa cartel led by Mexico's most-wanted drug lord Joaquin "Shorty" Guzman.
Camarena was kidnapped, tortured and murdered in retaliation for his involvement in successful drug busts.
Meade said the court ruling had not disrupted relations between Mexico and the United States.
More than 70,000 people have been killed in Mexican drug violence since 2007, when the previous government launched a militarized attack on warring cartels.
President Enrique Pena Nieto, who took office in December, has shifted the focus away from going after cartel bosses to fighting crimes such as extortion and kidnapping.