Two sons of Joaquín “El Chapo” Guzmán, one of Mexico’s most notorious cartel leaders, are in plea negotiations with the U.S. government over sweeping drug-trafficking charges, attorneys said Tuesday.

Joaquin Guzmán López, 38, recently began plea negotiations with federal prosecutors, attorneys confirmed in a Chicago courtroom. His brother Ovidio Guzmán López, 34, began plea negotiations in October, attorneys said at the time.

Both brothers initially pleaded not guilty, and neither appeared at the brief hearing on Tuesday.

“We need a bit more time,” Assistant U.S. Attorney Andrew Erskine said in court. “We’re trying to explore whether there might be a global resolution.”

Zambada has claimed that Joaquin Guzmán López kidnapped him and flew him aboard a private plane into the U.S., where Joaquin Guzmán López surrendered to authorities.

The FBI alleges Zambada and Joaquin Guzmán López oversaw the trafficking of “tens of thousands of pounds of drugs into the United States, along with related violence.” Zambada is due in court in New York next week.

Ovidio Guzmán López is due in court Feb. 27. Joaquin Guzmán López’s next court date is March 19.

The Associated Press contributed to this report.