MEXICO CITY (CNN) — At least 34 people have been questioned and Mexican prison officials fired as searchers hunt for notorious drug kingpin Joaquin “El Chapo” Guzman.

Monday night a recent picture of Guzman showed him with a shaved head and face, and without his trademark mustache, which he had when authorities captured him last year.

On Saturday it’s believed that the Sinaloa cartel leader stepped into a shower at the maximum security prison in Almoloya de Juárez, crawled through a hole and vanished through a mile-long tunnel apparently built just for him.

On Tuesday — despite a $3.8 million reward — there remains no sign of Guzman.

“The first 72 hours (after the escape) are extraordinarily important here,” said Mike Braun, a former chief of operations for the Drug Enforcement Administration who spent years tracking and gathering evidence on Guzman.

“And if they don’t get their hands on him then, I don’t know, we may never see this guy again.”

Mexican Interior Minister Miguel Ãngel Osorio Chong said Monday it was likely prison workers helped Guzman break out.

Guzman, he said, was inside a cell with 24-hour closed-circuit video surveillance and a bracelet that monitored his every move. The video system, he said, had two blind spots that Guzman exploited. And he left the bracelet behind before he crawled into the tunnel and made his getaway.

Nicknamed “Shorty” for his height, Guzman already had pulled off one elaborate escape from a maximum-security prison. In 2001, he managed to break free while reportedly hiding in a laundry cart. It took authorities 13 years to catch him — he was sleeping at a Mexican beach resort.

That he managed another prison break has U.S. officials fuming. When he was arrested in Mexico last year, the United States asked to have him extradited, in part because of concerns of an escape.

Guzman began plotting his latest prison break almost immediately.

According to internal Drug Enforcement Administration documents obtained by the Associated Press, agents were tipped off last year that Guzman’s relatives and associates were considering “potential operations to free Guzman.”

A U.S. official told the Associated Press that the DEA alerted Mexican officials. The Mexican Interior Secretary denied that assertion Monday night.

It’s possible Guzman is hiding out in the sprawling metropolis of Mexico City while the search is hot, a Mexican official told CNN.

But in the end, the official said it’s likely Guzman will head back to his home turf in the Sinaloa region on the Pacific Coast, where there’s a vast network of local residents who will help him stay out of harm’s way.

Just like the late al Qaeda leader Osama bin Laden famously hid in a remote, mountainous area of Afghanistan, Guzman is believed to have found refuge at times during his past stints on the lam in rugged mountain areas of Mexico.

“It’s like Tora Bora there,” the official said.

Guzman took a sophisticated route during his escape, officials believe: a tunnel complete with lighting, ventilation and even a modified motorcycle on tracks “that was likely used to remove dirt during the excavation and transport the tools for the dig,” Mexican National Security Commissioner Monte Alejandro Rubido said.

The tunnel began with a 50-by-50-centimeter (20-by-20-inch) opening inside the shower of Guzman’s cell, Rubido said. The tunnel stretched for about a mile and ended inside a half-built house.

It’s likely the Sinaloa cartel had spent years infiltrating the country’s prison system, a Mexican official told CNN on Monday. Whoever helped in the plot likely had the architectural plans for the prison that pointed them toward the shower area, the official said.

As authorities detailed the evidence they’d found pointing to Guzman’s escape through the underground passageway, one drug war expert questioned Monday whether the notorious kingpin even used the tunnel at all.

“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,” said Don Winslow, who’s tracked Guzman’s career for 15 years and wrote about a fictional version of the famed kingpin’s 2001 escape in his recent novel “The Cartel.”

“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.”

Guzman has been a nightmare for both sides of the border. He reigns over a multibillion-dollar global drug empire that supplied much of the marijuana, cocaine and heroin sold on the streets of the United States.

The U.S. Justice Department describes the Sinaloa cartel as “one of the world’s most prolific, violent and powerful drug cartels.” It says Guzman was considered the world’s most powerful drug lord until his arrest in Mexico in February 2014.

The 5-foot-6 Guzman, the son of a poor rural family, rose within the ranks of a cartel that should be thought of, said author Ioan Grillo, as a complicated network rather than a clearly organized company.

Grillo is a longtime journalist working and living in Mexico who wrote “El Narco: Inside Mexico’s Criminal Insurgency.”

“A cartel is not an organization with clear ranks or structure,” he said. “It’s something that operates in a geographical region where trafficking has gone on for a hundred years. You have people who are growers, smugglers, assassins, corrupt politicians and police on payrolls.”

A cartel is a network in which those working within it don’t necessarily know who else works for it, he said. That makes identifying a kind of CEO impossible. Guzman was an emblematic figure around which a legend grew, Grillo said. His legend is his power, and he uses his power in extremely violent ways.

“He is a complete savage,” Fuentes said. “What they do, and how they do business, is based on complete terror. … They kill journalists, politicians, police officers, corrections officers. And then not just that person, but every member of their family.”

The Sinaloa cartel moves drugs by land, air and sea, including cargo aircraft, private aircraft, buses, fishing vessels and even submarines, the Justice Department has said.

The cartel has become so powerful that Forbes magazine listed Guzman among the ranks of Bill Gates and Warren Buffett in its 2009 list of “self-made” billionaires. Guzman’s estimated fortune at the time was $1 billion.

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