Ismael 'El Mayo' Zambada Garcia, co-founder of Sinaloa cartel alongside El Chapo, in US custody

CHICAGO (WLS) -- One of the co-founders of the Sinaloa cartel and a son of Joaquin "El Chapo" Guzman have been arrested by U.S. authorities.

Ismael "El Mayo" Zambada and El Chapo's son Joaquin Guzman Lopez were taken into custody Thursday in El Paso, Texas, after being extradited to the United States, several sources told the I-Team before the U.S. government confirmed the news.

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Zambada, 76, has long been under indictment in Chicago on drug trafficking charges.

READ MORE | El Mayo and son: New indictment brings father and son narco tale back to the forefront

A leader of the powerful Sinaloa cartel for decades alongside Joaquín "El Chapo" Guzmán, Zambada was known for running the cartel's smuggling operations while keeping a lower profile. El Chapo was prosecuted in the U.S. and sentenced to life in prison in 2019.

The U.S. government had offered a reward of up to $15 million for information leading to El Mayo's capture.

"'El Mayo' and Guzman Lopez join a growing list of Sinaloa Cartel leaders and associates who the Justice Department is holding accountable in the United States. That includes the Cartel's other cofounder, Joaquin Guzman Loera, or 'El Chapo'; another of El Chapo's sons and an alleged Cartel leader, Ovidio Guzman Lopez; and the Cartel's alleged lead sicario, Néstor Isidro Pérez Salas, or 'El Nini,'" a statement from Attorney General Merrick Garland read in part. "Fentanyl is the deadliest drug threat our country has ever faced, and the Justice Department will not rest until every single cartel leader, member, and associate responsible for poisoning our communities is held accountable."

Zambada and Guzmán López are facing multiple charges "for leading the cartel's criminal operations, including its deadly fentanyl manufacturing and trafficking networks," Garland said.

In recent years, Guzman's sons have led a faction of the cartel known as the little Chapos, or "Chapitos" that has been identified as one of the main exporters of fentanyl, a deadly synthetic opioid, to the U.S. market.

"Garcia and Guzman have allegedly overseen the trafficking of tens of thousands of pounds of cocaine, heroin, methamphetamine, and fentanyl into the U.S. along with related violence. These arrests are an example of the FBI's and our partners commitment to dismantling violent transnational criminal organizations like the Sinaloa Cartel," a statement from FBI Director Chris Wray read in part.

They were seen as more violent and flamboyant than Zambada. Their security chief was arrested by Mexican authorities in November.

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Strong ties to Colombian cocaine suppliers and his cells across the United States made Zambada one of the most powerful drug traffickers in the world. He had been among the leaders of the Sinaloa Cartel since the 1970s, with their principal livelihood being the sale of narcotics in the United States, according to a U.S. Justice Department.

Zambada was an old-fashioned capo in an era of younger kingpins known for their flamboyant lifestyles of club-hopping and brutal tactics of beheading, dismembering and even skinning their rivals. While Zambada fought those who challenged him, he was known for concentrating on the business side of trafficking and avoiding gruesome cartel violence that would draw attention.

"El Mayo is one of DEA's most wanted fugitives and he is in custody tonight and will soon face justice in a U.S. court of law," a statement from DEA Administrator Anne Milgram read in part. "DEA will continue to seek justice for any American life that is lost and will work tirelessly to prevent more needless deaths and pursue those that are responsible."

The Associated Press and ABC News contributed to this report.

This is a breaking news story. Watch ABC7 Eyewitness News at 10 p.m. Thursday for more.