Top Mexican drug lord Joaquin 'El Chapo' Guzman, who fled from a maximum security jail for the second time, is believed to have used a long tunnel to pull the act off.
The tunnel that he used for escaping from Altiplano jail was more than 1 Kilometre-long, reported the BBC.
Eighteen guards are being interrogated in the case.
Mexico's National Security Commission said that the drug lord was last seen in Altiplano jail showers on Saturday.
He was the leader of the Sinaloa cartel, which smuggles huge amounts of illegal drugs into the U.S.
Guzman's recapture in 2014 was hailed as a victory for the Mexican Government.