Nkosi became a violent radical like the other Comrades because he suffered under the racist regime of South Africa and he hated white people and "traitors" who worked for them.
Nkosi led the Comrades to the home of Miyo Moshigo. He broke into the house with them and hit Miyo while others held him. Nkosi gave him back his glasses after Miyo was handcuffed with barbed wire and brought him to the outside where some Comrades were already waiting with a gasoline filled tyre. Nkosi joked around about it being a necklace that went nice with Miyo's glasses. He told Miyo that he had been found guilty of collaborating with the central government and wanted to set the tire on fire. Black Panther stopped Nkosi and beat up the Comrades. Nkosi tried to get to Miyo again, but he was once again stopped by the Panther. He got the chance to kick Miyo in the face after Black Panther stopped Miyo from attacking Nkosi. After that Nkosi attacked the Black Panther with the Comrades.
Nkosi was tackled to the ground by Miyo and wasn't able to stop him from fleeing. Shortly before the Fathers arrived, Nkosi dropped a burning match into the gasoline on the ground which set Theodore Olebogeng (who was an innocent six year old African boy who was at the scene trying to help his hero, Black Panther) on fire. One of the Fathers hit Nkosi hard on the head with a branch and he fell dead to the ground.
Theodore Oldbogeng would later die in hospital due to the burns caused by this event, arguably making Nkosi a child-murderer (though murder may be the wrong term as Nkosi didn't intentionally kill the boy).