The U.S. ambassador to Mexico confirmed that Ismael “El Mayo” Zambada, a key leader of the Sinaloa cartel, was forcibly brought to the U.S. against his will in July, contradicting speculation that he had turned himself in.

Zambada was allegedly kidnapped by Joaquín Guzmán López, a rival cartel leader and son of “El Chapo” Guzmán, during an internal cartel conflict.

The two were unexpectedly flown to Texas, where U.S. officials were surprised by their arrival.

Zambada’s attorney claims he was violently abducted and brought to the U.S., while Guzmán López, who had been negotiating his surrender, faces drug trafficking charges in Chicago, the Associated Press has reported.

The incident has heightened fears of increased violence within the Sinaloa cartel, prompting the Mexican president to appeal for peace among the warring factions.

Written by B.C. Begley