Ismael “El Mayo” Zambada got on an airplane to the U.S. believing he was going somewhere else, said the official, who spoke on the condition on anonymity because they were not authorized to discuss the matter. The official did not provide additional details, including who persuaded Zambada to get on the plane or where exactly he thought he was going.

Upon arriving in the El Paso area, Zambada and Joaquín Guzmán López, a son of notorious drug kingpin “El Chapo,” who was sentenced to life in a U.S. prison in 2019, were immediately taken into custody by U.S. authorities, officials said.

Zambada appeared in federal court in El Paso Friday morning and has entered a plea of not guilty to slew of drug trafficking charges, court records show. A lawyer listed for Zambada did not immediately respond to an email seeking comment Friday.

Zambada, one of the most powerful drug lords in the world, has been a key target for the U.S. government for years in its bid to take down leaders of the Sinaloa cartel that’s responsible for trafficking huge sums of drugs across the border. U.S. authorities had offered a reward of up to $15 million for information leading to his capture.

Zambada’s arrest “strikes at the heart of the cartel that is responsible for the majority of drugs, including fentanyl and methamphetamine, killing Americans from coast to coast,” said U.S. Drug Enforcement Administration chief Anne Milgram.

“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,” Attorney General Merrick Garland said in a statement Thursday evening.

Mexican President Andrés Manuel López Obrador said Friday that Mexico was still awaiting details about the arrests and was not involved in the operation. He hailed the arrests, though he suggested others could step in to fill the vacuum. That’s why his administration has focused on addressing the root causes of drug use and the associated violence, he said.

Mexican Security Secretary Rosa Icela Rodríguez said the plane took off with only the pilot from the airport in Hermosillo, Mexico. The flight tracking service Flight Aware showed the plane stopped transmitting its altitude and speed for about 30 minutes while it was over the mountains of northern Mexico before resuming its course to the U.S. border.

“It is a fact that one person went out from here, three people arrived there,” she said.

Zambada is charged in a number of U.S. cases, including in New York and California. Prosecutors brought a new indictment against him in New York in February, describing him as the “principal leader of the criminal enterprise responsible for importing enormous quantities of narcotics into the United States.”

One of the longest-surviving capos in Mexico, Zambada was considered the cartel’s strategist, more involved in day-to-day operations than his flashier and better-known boss, “El Chapo.”

Zambada is 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 has fought those who challenged him, he is known for concentrating on the business side of trafficking and avoiding gruesome cartel violence that would draw attention.

In an April 2010 interview with the Mexican magazine Proceso, he acknowledged that he lived in fear of going to prison and would contemplate suicide rather than be captured.

“I’m terrified of being incarcerated,” Zambada said. “I’d like to think that, yes, I would kill myself.”

The interview was surprising for a kingpin known for keeping his head down, but he gave strict instructions on where and when the encounter would take place, and the article gave no hint of his whereabouts.

Zambada reputedly won the loyalty of locals in his home state of Sinaloa and neighboring Durango through his largess, sponsoring local farmers and distributing money and beer in his birthplace of El Alamo.

Although little is known about Zambada’s early life, he is believed to have gotten his start as an enforcer in the 1970s. By the early 1990s, he was a major player in the Juarez cartel, transporting tons of cocaine and marijuana.

Zambada started gaining the trust of Colombian traffickers, allegiances that helped him come out on top in the cartel world of ever-shifting alliances. Eventually he became so powerful that he broke off from the Juarez cartel, but still managed to keep strong ties with the gang and avoided a turf war. He also developed a partnership with “El Chapo” Guzman that would take him to the top of the Sinaloa Cartel.

Zambada’s detention follows some important arrests of other Sinaloa cartel figures, including one of his sons and another son of “El Chapo” Guzmán, Ovidio Guzmán López.

Ovidio Guzmán López was arrested and extradited to the U.S. last year. He pleaded not guilty to drug trafficking charges in Chicago in September. The Bureau of Prisons inmate locator showed Ovidio Guzmán López was released Tuesday, but Rodríguez said U.S. authorities informed Mexico he was not freed but just had his custody changed.

In 2021, Zambada’s son pleaded guilty in federal court in San Diego to being a leader in the Sinaloa cartel.

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 a main exporter of fentanyl to the U.S. market. Their security chief was arrested by Mexican authorities in November.