Mexican authorities on Saturday abruptly transferred convicted drug lord Joaquin "El Chapo" Guzman from a prison outside Mexico City to a penitentiary near the border with the United States.
Guzman, the notorious Sinaloa drug cartel boss who has twice escaped Mexican prisons in recent years, was transferred under heavy security to Ciudad Juarez, which is separated from the U.S. state of Texas by the Rio Grande.
A Mexican government statement said the transfer from the maximum-security Altiplano prison was prompted by ongoing security upgrades at that facility, and it characterized the move as part of a periodic rotation of high-profile prisoners initiated last year.
Mexican security analyst Alejandro Hope told The Associated Press that authorities might have feared another attempt at a prison escape.
Guzman escaped from Altiplano in July 2015, in what was widely seen as a major embarrassment to the government of President Enrique Pena Nieto. He gained his freedom by crawling through a hole in his jail cell's shower to a 1.5-kilometer tunnel. He was captured six months later in a military operation in his home state of Sinaloa.
Guzman was first arrested in 1993, before escaping in 2001 from a prison in Guadalajara with the help of prison guards. He was apprehended 13 years later with information provided by U.S. intelligence agencies.