The name of the special operation's unit in the Guatemalan army strikes fear in those who remember the ruthless methods of this elite US-trained group.
The Kaibiles are infamous for their role in killing civilians during Guatemala's civil war. Their mission has since changed to help fight drug trafficking, but now they are faced with pursuing their own civil war.
Renegade and retired members of Kaibiles have been recruited by Mexico's Zetas drug gang, especially in the Peten and Alto Verapaz regions bordering Mexico.
They are being used to train the Zetas in the art of military warfare and the use of explosives.
Al Jazeera's Lucia Newman meets the Kaibiles in the Peten province of Guatemala.