Son of El Chapo pleads not guilty in Chicago as mystery cloaks cartel arrests

Joaquín Guzmán López, the son of Sinaloa cartel co-founder Joaquín “El Chapo” Guzmán Loera, has pleaded not guilty to drug trafficking charges in federal court in Chicago, days after his arrest in a dramatic operation in which he may have delivered his father’s former business partner to US authorities.

Guzmán López, 38, was detained on Thursday alongside Ismael “ El Mayo ” Zambada García, the other co-founder of one of Mexico’s most powerful organised crime groups, after touching down in a small plane in El Paso, Texas.

Wearing an orange jumpsuit but no handcuffs, Guzmán López entered the plea at a hearing that lasted about 10 minutes.

Related: Top leaders of powerful Sinaloa drug cartel arrested in Texas

While El Chapo is already serving a life sentence in the US , El Mayo evaded arrest for decades, despite the $15m bounty on his head. Zambada pleaded not guilty to all charges in a court appearance last Friday.

US officials told their Mexican counterparts – who had been in the dark about the operation – that Guzmán López handed himself in, but have provided confused accounts of the nature of El Mayo’s arrest.

Two theories have been floated in a frenzy of speculation: either El Mayo also handed himself in, or he was betrayed by Guzmán López, perhaps in return for better terms for him and his brother, Ovidio Guzmán López , who is currently on trial in the US.

El Mayo is believed to be in his late 70s and, by some accounts, sick from cancer and diabetes, which may suggest a motive for negotiating his own arrest with the US, where several of his close family members are already in prison.

However, US law enforcement sources initially briefed that Guzmán López had tricked El Mayo into boarding a plane to inspect clandestine airfields before instead taking him to the US.

Then, over the weekend, El Mayo’s lawyer rejected both accounts, saying that his client had been violently abducted.

“Joaquín Guzmán López forcibly kidnapped my client. He was ambushed, thrown to the ground, and handcuffed by six men in military uniforms and Joaquín. His legs were tied, and a black bag was placed over his head,” Frank Pérez said in a statement over text. “He was then thrown into the back of a pickup truck and taken to a landing strip. There, he was forced onto a plane, his legs tied to the seat by Joaquín, and brought to the US against his will.”

This version of events could be a smokescreen to conceal a deal between El Mayo and US authorities. But the Chapitos – the faction of the Sinaloa cartel led by El Chapo’s sons – have yet to deny the accusation of betrayal.

Asked about the kidnapping allegation, Jeffrey Lichtman, Guzmán López’s lawyer, said: “Mr. Zambada is free to employ any defence he’d like against the charges he faces.”

Related: ‘Nada cambia’: Mexican drugs lord ‘El Mayo’ has been captured, but does targeting kingpins work?

Amid the secrecy and intrigue, Andrés Manuel López Obrador, Mexico’s presideent, has called on the US to explain exactly what happened.

The issue is diplomatically tense, both for the suggestion that the US acted unilaterally and the prospect that Guzmán López and El Mayo traded information about political corruption in Mexico for better deals.

If El Mayo was indeed betrayed by Guzmán López, there could be a surge of violence between their factions of the Sinaloa cartel, which have been fighting on-and-off since El Chapo’s arrest in 2017.

Rival criminal groups – not least the cartel Jalisco Nueva Generación, which is locked in violent struggles with the Sinaloa cartel across Mexico – may also see an opportunity to expand their influence.

On Monday, López Obrador took the unusual step of issuing a public appeal for the criminal groups not to fight each other following the arrests, while also sending extra troops to Sinaloa just in case.

North of the border, the Biden administration heralded the arrests as a blow against the trafficking of fentanyl, the synthetic opioid fuelling an overdose crisis in the US that claims roughly 70,000 lives a year.