In an announcement Wednesday, the Mexican Attorney General’s office confirmed it is issuing charges against Joaquín Guzmán López, who is in US custody in Chicago.

“An order of apprehension is being prepared alleging kidnapping and illegal deprivation of liberty of an individual on national territory in order to hand them over to authorities in another country,” Mexico’s Attorney General wrote in the statement.

The office also said investigators have secured the vehicles and property believed to have been used in the act. Though they did not elaborate, they also stated the air strip where the flight originated has been identified.

The announcement comes about a month after Guzmán López – one of El Chapo’s sons, known as the “Chapitos” – flew in a private plane to a small airfield near El Paso, Texas, along with the notorious 76-year-old narco boss Ismael “El Mayo” Zambada. Both were taken into custody by US law enforcement on longstanding charges of running one of the most powerful narcotics trafficking organizations in the world.

The cartel is thought to be responsible for the trafficking of vast amounts of cocaine, heroin, methamphetamine and fentanyl into the US. DEA Administrator Anne Milgram said the arrests strike “at the heart of the cartel that is responsible for the majority of drugs, including fentanyl and methamphetamine, killing Americans from coast to coast.”

The surprise arrest raised questions about why they took that flight and what happened beforehand. Mexican officials have said they believe Joaquín Guzmán López made an agreement with his imprisoned brother Ovidio before the flight, but an attorney for Ovidio told CNN the claim was “a complete and utter fabrication.” Ovidio Guzmán López was extradited to the US in 2023 and is awaiting trial on drug and money laundering charges.