By Claire Marshall
BBC, Mexico City
Federal authorities in Mexico are investigating the escape of an alleged drugs baron from a prison in the capital, Mexico City.
It is not clear when Mr Herrera Garcia escaped
This comes after another breakout from a jail earlier this month in a different part of the country.
The man now said to be on the run is Otto Roberto Herrera Garcia.
Until his April 2004 arrest at the city's airport, he was one of Central America's most wanted, accused of moving tons of cocaine into the US.
He is alleged to be a boss of a Guatemala-based drugs trafficking gang.
The US had offered $2m for information leading to his capture.
It is thought that Mr Herrera Garcia has links to Mexico's most notorious drugs baron, Joaquin "El Chapo" Guzman, who also escaped from prison four years ago.
Mexico's federal authorities discovered that Mr Herrera Garcia was missing from prison during a security operation on Friday night.
He may have escaped several days ago.
Forty-five jail employees have been detained for interrogation.
It is unclear why such a high-profile inmate was not being detained at a maximum security penitentiary.
This highlights once again the weaknesses in Mexico's prison system.
Nine inmates escaped from a jail in the west of the country earlier this month.
At the beginning of the year, troops were sent in to secure several top-security prisons near Mexico City over fears that drug traffickers were plotting to escape.