Guzman's escape is a major embarrassment to the Pena Nieto administration, which had received plaudits for its aggressive approach to top drug lords. Since the government took office in late 2012, Mexican authorities have nabbed or killed six of them, including Guzman.
Guzman faces multiple federal drug trafficking indictments in the US as well as Mexico, and was on the US Drug Enforcement Administration's most-wanted list.
After Guzman was arrested on Feb. 22, 2014, the US said it would file an extradition request, though it's not clear if that happened.
The Mexican government at the time vehemently denied the need to extradite Guzman, even as many expressed fears he would escape as he did in 2001 while serving a 20-year sentence in the country's other top-security prison, Puente Grande, in the western state of Jalisco.
Former Mexican Attorney General Jesus Murillo Karam told the AP earlier this year that the US would get Guzman in "about 300 or 400 years" after he served time for all his crimes in Mexico.
He dismissed concerns that Guzman could escape a second time. That risk "does not exist," Murillo Karam said.
"It wasn't overconfidence; it was Mexican judicial nationalism," said Raul Benitez, a security expert at Mexico's National Autonomous University. "First he had to pay his debt in Mexico and then in the US. Now it's very evident that it was a mistake."
It was difficult to believe that such an elaborate structure could have been built without the detection of authorities, though photographs show the corrections facility surrounded by construction, with large open ditches and lots of metal drainage pipes that could have camouflaged such a project.
Guzman dropped by ladder into a hole 10 meters (30 feet) deep that connected with a tunnel about 1.7 meters (5 feet-6 inches) high that was fully ventilated and had lighting, Rubido said.
Authorities also found tools, oxygen tanks and a motorcycle adapted to run on rails that they believe was used to carry dirt out and tools in during the construction.
The tunnel terminated in a half-built house in a farm field, according to radio transmissions among authorities, who cordoned off the structure that sits atop a small rise with a clear view of the prison. They would not confirm the location of the end of the tunnel directly.