In his last moments as Mexico’s most important prisoner, Joaquín “El Chapo” Guzmán paces his cell, past his single bunk with rumpled sheets, the plastic water jugs on the floor. He seems particularly interested in what’s behind the waist-high wall of the shower stall, as he keeps bending down to look at the floor.

It is Saturday night, about 9 p.m., inside Cell 20 of the Altiplano maximum-security prison, and the video surveillance camera captures Guzmán’s shadow as it traces across the walls. The 60-square-foot room is inside the wing for the country’s most dangerous criminals, where the drug lord Guzmán has spent the past year and a half in solitary confinement under 24-hour surveillance, a monitoring bracelet on his wrist.

As the video shows, Guzmán sits down on the edge of his bunk and slips off his shoes. He pads back to the shower, kneels behind the wall and vanishes.

On Tuesday, Mexican authorities released the surveillance footage of Guzmán’s dramatic prison escape.

And on Wednesday, prison guards allowed reporters to visit Guzmán’s empty cell, the last of 10 cells at the end of a narrow paint-splattered hallway inside the slate-gray prison. From the front door of the prison, a visitor must pass through metal detectors, turnstiles, observation rooms, up and down flights of stairs, and through 15 locked ­metal-bar gates, several with ­finger-print ID sensors, before reaching the ­special-treatment wing, the one reserved for the country’s most dangerous criminals. 

“Have you reached the point where you feel that life is not worth living?” a suicide-prevention poster reads at the entrance of Guzmán's hallway. 

His moldy ground-floor cell felt more cramped than the video portrays, with low ceilings, about eight-feet high, and a small window looking out onto more walls and barbed-wire fencing. The thin mattress rested on a concrete slab. There was no toilet but a hole in the ground, a sink with one faucet, and a concrete desk with a stool bolted to the floor. 

Behind the shower wall, one of the blind spots for the surveillance camera, Guzmán’s allies had cut a square hole in the roughly two-inch-thick reinforced concrete floor, leading down into the draft blackness. Pinpointing the location of this shower stall ­required feats of engineering — or inside help — that have yet to be fully explained. Authorities said the hatch dropped 30 feet underground to a tunnel that ran to a cinder-block house in the cornfields south of the prison. 

Guzmán lifted the heavy concrete slab and descended by ladder out of the cell. 

The tunnel, full of pumped-in oxygen, was equipped with a motorcycle on rails used to ferry dirt and supplies. Guzmán likely rode it on his way through the nearly mile-long tunnel, well before authorities recognized he had ­escaped and launched a manhunt to find him. Mexican officials said that prison officials sounded the alarm about a half-hour after his disappearance, locking down the other prisoners and not allowing anyone to enter or exit the prison.

In the four days since his disappearance, Mexican authorities have failed to explain how their prized prisoner could have outfoxed the country’s most ­secure prison. Interior Minister Miguel Ángel Osorio Chong has said that prison officials must have colluded with Guzmán to help him flee.

So far, three top justice officials have been fired, including the prison’s director, Valentín Cárdenas Lerma. The government is questioning them and several others about the escape.

After initial hesitation, the Mexican government has agreed to accept the offer by the United States to help try to find and rearrest Guzmán, the leader of the Sinaloa cartel, which is responsible for transporting a large portion of the cocaine and heroin that reaches the United States.

Members of the FBI and the Drug Enforcement Administration met with representatives of the Mexican attorney general’s office this week to discuss the search efforts. After Guzmán’s arrest in February 2014, American officials had pressed for his extradition, but the Mexican government decided to keep him imprisoned.

The issue of cooperation between the two countries is a delicate one because of Mexico’s long-standing suspicions about American meddling. At the start of President Enrique Peña Nieto’s administration, the Mexican government halted many aspects of the two countries’ security coordination, concerned that U.S. law enforcement was too deeply involved in Mexican matters.

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