Z-40 moved to Juarez prison where Chapo was held before extradition.
Mexican authorities say they have transferred the leader of the brutal Zetas drug cartel to the same border prison that held Joaquin "El Chapo" Guzman before he was extradited to the United States in January.
A federal official not authorized to be quoted by name says Miguel Angel Trevino Morales was transferred from the Altiplano prison west of Mexico City to a federal prison in Ciudad Juarez, across the border from El Paso, Texas.
The official said Monday the transfer was a routine preventative measure to avoid escapes.
However, Guzman underwent the same transfer just before he was extradited.
Trevino Morales is known as "Z-40." U.S. prosecutors in Texas have charged him with money laundering, but it is unclear if there is a current extradition request for him.