MEXICO CITY >> Alleged Mexican kingpin Ismael “El Mayo” Zambada has pleaded not guilty to U.S. drug trafficking charges, court records showed today, after he and a son of another drug lord were arrested on Thursday in El Paso, Texas.

Court records showed that Zambada today waived his right to appear personally in court and directed that a not guilty plea be entered on his behalf.

He was ordered detained without bond and is scheduled to be arraigned before U.S. Magistrate Judge Anne Berton next Wednesday, the records showed. His lawyer did not immediately respond to requests for comment.

Both Zambada and Joaquin Guzman Lopez, a son of Joaquin “El Chapo” Guzman, face multiple charges in the U.S. for funneling huge quantities of fentanyl and other drugs to U.S. streets.

Their detentions were a dramatic achievement for U.S. law enforcement that could also shake up the Mexican drug landscape.

Mexico’s government was informed of the detentions by the U.S. government, but Mexican authorities did not participate in the operation, Mexican Security Minister Rosa Rodriguez said today.

Rodriguez added that it was unclear if Zambada and Guzman Lopez handed themselves over to U.S. authorities voluntarily.

“The Mexican government did not participate in this detention or surrender,” Rodriguez said at a press conference.

Zambada, who is believed to be in his 70s, and Guzman Lopez, who is in his 30s, were detained after landing in a private plane in the El Paso area.

Zambada co-founded the Sinaloa Cartel with El Chapo, who was extradited to the U.S. in 2017 and is serving a life sentence in a maximum-security prison.