A private zoo with exotic animals, four private planes and trips to Switzerland for anti-aging treatments – all part of the lavish lifestyle of Mexican drug lord Joaquin “El Chapo” Guzman during the early 1990’s “cocaine boom,” according to testimony from a onetime close friend and top assistant.

A top lieutenant of the Sinaloa cartel from 1986 to 1998, Miguel Angel Martinez testified in federal court on Tuesday against his former boss who was brought to New York City to face drug conspiracy charges.

Martinez called the business “the best thing in the world” in the early 1990s as the cartel was a vital part of the “cocaine boom” and as a result, they “made a lot of money.”

He recalled receiving payments of up to $10 million every month by means of private jets. He said they stashed the cash wherever they could find the space for it.

Martinez testified that El Chapo had acquired four jets, a $10 million beach house in Acapulco (among many others), “ranches in every state,” and traveled all over the world at the height of the drug-business boom.

Guzman also allegedly had his own private zoo that held lions, panthers, tigers and deer -- and included a small train on which visitors could travel across the grounds.

El Chapo was said to have his own yacht and even gifted his employees with cars.

Over time, the kingpin who grew up in poverty developed a taste for world travel, he said. His entourage visited Macau to gamble and Switzerland so he could get a "cellular youth treatment," he said.

The former lieutenant also recalled in court having to pay for El Chapo's multiple wives. Emma Coronel Aispuro, who married the drug kingpin in 2007, was said to be looking down during this portion of the testimony.

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Martinez described how the Sinaloa cartel was smuggling tons of cocaine into the United States — through tunnels dug under the border, in tanker trucks with secret compartments, even in fake chili pepper cans. What came back in the other direction, he said, was tens of millions of dollars in cash.

Much of it ended up in Tijuana, where Guzman would send his three private jets each month to pick it up, Martinez said. On average, each plane would carry up to $10 million, he said.

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Guzman was extradited to the U.S. last year from Mexico. He has pleaded not guilty to drug-trafficking charges, with his lawyers claiming he's being framed by shady cooperators.

In opening statements, a defense attorney suggested Martinez couldn't be trusted as a witness, saying he had such a severe cocaine habit while he was working for Guzman that it damaged his nose. He admitted Tuesday that "unfortunately" he was using up to 4 grams of coke each day at the time, but hadn't touched it for 20 years.

Fox News Tamara Gitt and The Associated Press contributed to this report.