The extradition of drugs lord Joaquin "El Chapo" Guzman to the United States has been given the green light by a judge in Mexico.
Mexico's foreign ministry now has 20 days to decide whether to approve his extradition and Guzman also has the right to appeal.
Mexico's Judicial Council said the judge had agreed the legal requirements laid out in the extradition treaty between the two countries had been met.
Any extradition attempt can be delayed or stopped by a request to the court by lawyers for the Sinaloa cartel leader.
Guzman was moved on Saturday from a prison outside Mexico City to one in Ciudad Juarez near the US border. Questions have been raised about the decision to relocate the convicted drug lord to a region that is one of his cartel's strongholds.
A Mexican security official has confirmed transfer was to a less secure prison.
The official said the Cefereso prison on the outskirts of Ciudad Juarez, across from El Paso, Texas, is not as impregnable as the maximum-security Altiplano facility near Mexico City where he had been held.
Guzman is being held in a maximum-security wing where the same protocols are being enforced as in Altiplano, including 24-hour monitoring via a camera in his cell.
Guzman first broke out of another prison in 2001 and spent more than a decade on the run, becoming one of the world's most-wanted fugitives. He was recaptured in 2014, but slipped out of Altiplano, which many previously had thought was inescapable, in July 2015 by fleeing through a sophisticated, mile-long tunnel that went up into the shower in his cell.
Mexican marines re-arrested him in the western state of Sinaloa in January.
He was returned to Altiplano, where he was placed under constant observation from a ceiling camera with no blind spots, and the floors of top-security cells were reinforced with metal bars and a 16-inch layer of concrete.
Media reports are speculating that the move suggests an imminent extradition to the US, where he faces drug charges in seven jurisdictions but this is denied by authorities.
A lawyer for Guzman said his defence continues to fight the drug lord being sent to the US and officials have said it could take up to a year to reach a final ruling.