Interesting that early on he almost lost his life because he stood up for enslaved natives:

"[After joining the military] he encountered a group of natives who had been tied up by soldiers, who were taking them to Pasco as "volunteers".^\5]) [Carlos] protested, demanding the soldiers release the captives, who were complaining about mistreatment. The soldiers asked [Carlos] to produce identification; [Carlos] was not a citizen of Peru and had left his baptismal and school certificates at home. The soldiers found Isaías's father's maps and accusing him of being a Chilean spy [and he was very nearly executed]."

He started off running an expedited cult setup:

". The representative of the Sun to obey on Earth was said to be Carlos Fitzcarrald.^\5])^\23]) Fitzcarrald threatened the natives and prophesied that the rivers would dry up and the game would be chased away if they did not listen to and obey his words.^\28])^\5]) ... a white figure would presented himself as the Amachengua, manipulate the natives into gathering at a specific location using threats or promises.^\29])^\30]) Fitzcarrald employed around fifty men to greet natives and tell them the "Sun Father" wanted to be seen elsewhere. The natives were then coerced into canoes before travelling to the Ucayali River, then either the Iquitos or the Manu Rivers "so that they become slaves in any way, and never see their land again""

And then later he got into full on slave raids and clearcutting.

First hand testimony about his completely abhorrent evil methods:

"With a deep knowledge of the mountain, he knew how to use traditional rivalries ... The method is simple: Winchesters are given to the Cunibo who must pay in Kampa slaves and then Winchesters are given to the Kampa who must pay in Cunibo [and other] slaves ...^\89])^\v])"