Two top leaders of the Mexican Sinaloa drug cartel have been taken into custody by United States authorities to face charges for their role in leading the group’s vast drug trafficking enterprise, the Department of Justice announced Thursday.

Sinaloa cartel co-founder Ismael “El Mayo” Zambada and Joaquin Guzman Lopez, the son of “El Chapo” Guzman, were placed under arrest in El Paso, Texas, on Thursday, according to Attorney General Merrick Garland.

“Both men are facing multiple charges in the United States for leading the Cartel’s criminal operations, including its deadly fentanyl manufacturing and trafficking networks,” Garland said in a statement. “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.”

Zambada made his initial appearance Friday morning in El Paso federal court before Judge Anne Berton, according to court records. He pleaded not guilty to the 12 charges in his 2012 indictment in the Western District of Texas and was ordered detained pending his next hearing, scheduled for July 31, according to court records.

Zambada, 76, required the use of a wheelchair and made no other statements other than responding to Berton with “Yes,” “No,” or “Yes, I understand,” as she questioned him, according to a transcript of the proceedings obtained by ABC News.

During the proceedings, Berton said that Ray Velarde, an attorney who plans to join the case, has an outstanding conflict in representing Zambada which the defendant would be permitted to waive if he chooses. The judge did not address the nature of the conflict.

Zambada faces multiple federal indictments in jurisdictions across the U.S. for his alleged role in the cartel and has been on the run from U.S. and Mexican law enforcement for years. His fellow co-founder of the Sinaloa cartel, Joaquín “El Chapo” Guzman, was extradited to the U.S. in 2017, convicted in 2019 and sentenced to life in prison.

“Today, the FBI and DEA arrested two alleged cartel leaders who have eluded law enforcement for decades. Ismael Mario ‘El Mayo’ Zambada García and Joaquin Guzman Lopez, son of El Chapo, will now face justice in the United States,” FBI Director Christopher Wray said in a statement.

“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,” Wray said.

The men were arrested in an operation that ended on U.S. soil.

“El Mayo” thought he was headed to inspect a clandestine Mexican airfield, of which the Sinaloa cartel has many in the country. Instead, according to a Homeland Security Investigations official, a senior ranking member of the cartel tricked him and flew him to El Paso instead.