The engineers who built the tunnel were flown to Germany for specialized training, Penn said. A motorcycle on rails inside the tunnel was adjusted to run in an environment with limited oxygen, he said.

While Penn does not give the specific location of the interview, he said it was conducted in Mexico.

Guzman was recaptured early Friday when the Mexican navy raided a home in the coastal city of Los Mochis, where he was protected by many local residents who revered him as a modern Robin Hood.

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Not blindfolded

In the article, Penn mused about the fact that he was not blindfolded while going to meet the drug lord.

But he also highlighted the extraordinary measures taken to protect Guzman, including flying Penn and his team aboard a plane that had a device that jams radar and ensuring they did not have their phones.

That night, after a few hours of talking, Guzman and his protectors strapped on body armor and brought out the weapons.

Penn said the interview was planned by Kate del Castillo, a Mexican actress who supported Guzman. The drug lord wanted the actress’s help in spearheading a movie project about his life.

Del Castillo has not commented since the publication of the article. Authorities want to question Penn and del Castillo, a senior Mexican law enforcement official said.

Tracking cell phones

Questions have swirled over what role, if any, the interview had on his arrest Friday.

Before the interview came to light, two U.S. law enforcement officials had said tracking of cell phones and electronic exchanges among people close to Guzman was critical in his recapture.

Mexican authorities said they captured Guzman partly because he or his representatives contacted filmmakers and actors about making his biopic.

It’s unclear whether authorities were referring to Penn and del Castillo.

His thoughts on Donald Trump

Penn said he and Guzman discussed various topics, including Republican presidential candidate Donald Trump, whom Guzman referred to as “mi amigo.” Trump has been highly critical of illegal migration of Mexicans to the United States.

Guzman also defended his drug business, saying the Mexican economy and lack of jobs left him with no choice.

On the topic of his own mortality, he said he hoped to die of “natural causes,” not in a shootout.

Back to the same prison

After six months on the run, Guzman is now back in the same maximum security prison from which he escaped, a Mexican law enforcement official said.

And the Sinaloa cartel leader may be extradited to the United States, where he faces drug trafficking charges.

Interpol agents served extradition paperwork Sunday in the prison where Guzman is being held, the Mexican attorney general’s office said.

The process could take months, and he would have the right to appeal.

Guzman is included in at least seven drug-related indictments in various U.S. jurisdictions. The United States had sought his extradition in June before he escaped, Gomez said.

Guzman’s lawyers have filed documents to fight extradition.

History of prison escapes

Guzman’s July prison escape — his second in 14 years — embarrassed the Mexican government.

Authorities first arrested Guzman in Guatemala in 1993 and extradited him to Mexico. After his conviction, he escaped from a maximum security prison in 2001, using a laundry cart, and evaded Mexican authorities for years.

His freedom ended in 2014, when he was arrested in the Mexican resort town of Mazatlan.

In the latest hunt for Guzman, there were reported sightings and near-misses.

In October, the same month Penn interviewed him, authorities said they almost caught him but he slipped away.