Four more Mexican officials have been formally charged after being suspected of aiding the July escape from prison of notorious drug lord Joaquin “El Chapo (Shorty)” Guzman.

Mexico’s federal judicial council said in a statement on Monday that two of those charged were prison employees tasked with the video monitoring of El Chapo’s cell and two were members of the Mexican intelligence service, who also worked at the high-security Altiplano Prison in central Mexico at the time.

The charges brought against the four say they failed to alert others of Guzman’s escape in a timely fashion.

A view of the entrance of the Altiplano Prison in the town of Almoloya de Juarez, Mexico, July 12, 2015. (AFP photo)

The drug kingpin escaped from prison through a tunnel dug in his cell on July 11.

The tunnel, 1.5 kilometers (one mile) long, was dug in his shower area, and footage shows Guzman walking in before disappearing from sight and going underground.

A view of the hole (L) in the shower of the prison where “El Chapo Guzman” used to escape, on July 15, 2015 (Photo by AFP)

Guzman is the leader of the Sinaloa drug cartel, which smuggles huge amounts of illegal drugs into the United States. He busted out of another maximum security penitentiary in 2001.

Mexican President Enrique Pena Nieto had billed his arrest last year as his biggest victory yet in his trademark war on drugs.

Three other Mexican prison workers were charged several weeks ago with aiding the 58-year-old in his jailbreak.