He's believed to have broken his leg and injured his face in the fall, the official said.
The pursuit came after Mexican Marines and other special forces spotted the Sinaloa cartel chief on October 9 near the town of Cosala, in the mountains of Mexico's Sinaloa state, the official said. At the time, he was with a girl, and authorities were reluctant to move in. Later, when they spotted him without the child, the official said, the special forces pursued Guzman on foot.
As they closed in, the official said, Guzman fell off the cliff. His bodyguards rushed to the bottom of the cliff, carried Guzman away and were able to escape in the dense forest, according to the official.
Guzman broke out of a Mexican maximum-security prison
through an underground tunnel
in July. Last week authorities revealed Guzman had recently escaped again
while they were on his trail, and had injured himself as he slipped out of sight. At the time, they did not provide specifics on the date and exact location of the operation, or detail how Guzman was injured.
Pilot's capture helping hunt?
Nicknamed "Shorty" for his height, Guzman broke free once before from a maximum-security prison, in 2001, reportedly hiding in a laundry cart.
Government officials hailed his capture in 2014 as a sign they were winning the drug war. His July escape sent authorities scrambling and sparked widespread criticism of corruption in Mexico
Since the brazen breakout, officials have said they've arrested dozens of people -- all but one of them government employees -- and collected nearly 200 pieces of evidence.
At least one of the arrests appears to have helped investigators home in on Guzman's whereabouts: the drug lord's pilot
Authorities concentrated on the area of Cosala, the Mexican official said, because of data they obtained from digital instruments inside Guzman's private plane. From the readings, they observed that the pilot had flown to various places to get supplies for Guzman, but always returned to the same airstrip, the official said.
Where did Guzman go?
The Mexican official said Guzman got away during his latest brush with authorities because the special forces pursuing him were still on foot. But the official said authorities have spotted the Sinaloa cartel chief several times this month.
On October 6, they saw him in Mexico's Durango state with his sons. He was seen on a motorcycle and in a Ferrari, the official said.
Because of Guzman's recent injuries, the official said, their chances of capturing Guzman "have boosted tremendously."
Other experts have also painted it as a positive sign.
"The fact that he's injured is one factor he didn't count on. ... Now he needs help," former Drug Enforcement Administration Special Agent Carl Pike said.
Having to tend to his injuries, Pike said, will slow down Guzman.
"It puts him in one particular spot that he wasn't planning on being in before," Pike said.
But still, Guzman has proven that he's a moving target and isn't easy to find.
Guzman is still being protected by residents in the area, the official said, especially those near his hometown in Sinaloa.