Prosecutors at the trial of the drug lord Joaquín Guzmán Loera spent more than 10 weeks painting the kingpin as the most despicable sort of criminal. Mr. Guzmán, known as El Chapo, trafficked tons of drugs, bribed nearly everyone of authority in Mexico and once ordered his henchmen to incinerate the bodies of two of his enemies in a bonfire, they said.

But on Friday night, two days before jurors were set to begin deliberations, the prosecutors unsealed secret documents revealing a series of even more shocking claims against Mr. Guzmán. The most disturbing were accusations that the crime lord once raped one of his mistresses and routinely raped girls as young as 13 years old, sometimes drugging them by placing “a powdery substance” into their drinks.

Mr. Guzmán’s lawyer, A. Eduardo Balarezo, immediately discounted the accusations, issuing a statement on Saturday that said: “Joaquin denies the allegations.”

In the statement, Mr. Balarezo noted that the claims “lack any corroboration and were deemed too prejudicial and unreliable to be admitted at trial.” He added: “It is unfortunate that the material was publicly released just prior to the jury beginning deliberations.”