Mexico's attorney general said Tuesday the government would appeal the court ruling that set free Rafael Caro Quintero, a drug lord convicted of killing a US drug agent in 1985.
Attorney General Jesus Murillo Karam said during a public event that the government was "preparing" an appeal to overturn the verdict, which set Caro Quintero free 28 years into a 40-year sentence.
Murillo Karam declined to respond when asked if the government knew the current whereabouts of the 60-year-old, who left prison on Friday.
Caro Quintero was convicted of ordering the 1985 abduction, torture and killing of US drug enforcement agent Enrique Camarena and his Mexican pilot Alfredo Zavala.
Caro Quintero had another 12 years to go in his sentence, and could have faced additional charges in the United States, but on August 7 a judge in the western state of Jalisco ordered his release on a technicality.
The US National Security Council said Sunday it was "deeply concerned" by Caro Quintero's release, and feared another individual connected to the Camarena killing could also be set free.
Mexican Foreign Minister Jose Antonio Meade downplayed the dispute over the release, saying it would not affect relations with Washington because both governments opposed the court ruling, which he said should be "revised."
Caro Quintero was a leading figure in the Guadalajara Cartel, a now-defunct organization that was one of the early Mexican drug mafias that linked up with Colombian criminals to smuggle cocaine and other drugs into the United States.