The authorities' hunt continues for Mexican Drug Lord Joaquin "El Chapo" Guzman after his tunnel escape from a maximum-security prison west of Mexico City on Saturday.

Just how did "El Chapo" managed to escape from behind the bars, and under the noses of prison guards?

According to CNN, "El Chapo" used a tunnel in the shower area of his cell to escape. The Guardian reported that the tunnel was a mile-long and 2 feet-wide that led to an abandoned house.

"You cannot build a mile-long tunnel and get into this without some level of corruption," said Ioan Grillo, author of "El Narco: Inside Mexico's Criminal Insurgency."

This is not the first time that "El Chapo" escaped from prison. The drug kingpin was also able to pull off an escape in 2001 when he hid in a laundry cart breaking free from behind the bars. It was only in February 2014 when "El Chapo" was recaptured in a seaside resort in Mexico.

Don Winslow, who has tracked Joaquin Guzman's career for one and a half decades wrote a fictional version of his 2001 escape in his recent novel "The Cartel." According to Winslow, it is highly unlikely that prison guards were involved in the escape plan.

"If he went out that tunnel, it was with an armed escort, most likely a mix of prison guards and his own people, if the past is prologue," Don Winslow said.

"My bet is that he went out the front gate, and the tunnel was a tissue-thin face-saving device for Mexican officials, the motorcycle a dramatic improvement over the laundry cart."

According to Yahoo! News, the US Drug Enforcement Administration had already alerted Mexican authorities about several plans to free "El Chapo" 16 months ago. The DEA allegedly got information last year that Guzman's relatives and drug-world associates were undertaking operations to get him out of prison.