Convicted drug lord Joaquin "El Chapo" Guzman, who twice pulled off brazen jailbreaks, was transferred to a prison in northern Mexico near the Texas border early today.
The Sinaloa cartel boss was moved from the maximum-security Altiplano lock-up near Mexico City to a prison in Ciudad Juarez, across the border from El Paso, a security official told The Associated Press, without giving a reason for the transfer.
Jose Refugio Rodriguez, a lawyer for Guzman, confirmed that he was sent to the Cefereso Number 9 prison. He said Guzman's defence team was not notified beforehand, and one of his lawyers was travelling to Juarez to try to meet with their client.
"I don't know what the strategy is," Mr Refugio said. "I can't say what the government is thinking."
Guzman's lawyers are appealing against a bid to have him extradited to the United States, where he faces charges in multiple jurisdictions.
"El Chapo" first broke out of a Mexican prison in 2001. He was recaptured in 2014, only to escape the Altiplano prison the following year through a mile-long tunnel dug to the floor of the shower stall in his cell.
Mexican marines re-arrested him in the western state of Sinaloa in January, after he fled a safe house through a storm drain.
He was returned to Altiplano, where officials beefed up his security regimen.
Guzman 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.