Although Joaquin “El Chapo” Guzmán's prison escape on July 11 led to some speculation that prison guards were in on the break out, footage recently shown on Mexican TV suggests that the guards were in the dark.

The CCTV footage, which shows a full 26 minutes passing before guards even realized that the drug lord had escaped from his cell, is a longer version of recordings previously released by the government. The audio, which was missing from the initial video, implies that the guards were unaware of the Guzmán's escape.

As the BBC reports, a guard calls out, "Guzmán? Guzmán?" then tells his commander that there is "a hole in the shower drain."

The commander asks about the size of the hole, and the guard responds, "Big, boss, big."

"Listen, and the inmate is not there?" the commander asks.

"No, boss, he's not," the guard responds.

Prior to his escape, loud hammering can be heard and Guzmán is seen turning up the volume of his TV to block out the sound. Throughout the noise of the drilling and the hammering, the guards, who were watching security monitors, appeared to be unaware of the escape that is about to occur.

Guzmán's escape from the maximum-security prison in Altiplano was an embarrassment to President Enrique Peña Nieto’s administration, but should not have come as too much of surprise, as underground tunnels appear to be the go-to escape route for cartel criminals.

Guzmán had previously evaded Mexican marines by disappearing into a series of subterranean passageways that linked up to seven houses.

Adelmo Niebla González, a fellow cartel operative, tunneled out of his cell about 14 months before Guzmán's latest escape.

As The New Yorker reports, in the last 25 years, officials have come upon 181 secret passages under the U.S.-Mexico border, some reaching as deep as 70 feet.