It has been my strong belief that Fidel Castro had worked with the CIA to bring Che Guevara to his demise. The documentary also hinted at this several times. The first when when the interviewees talked about how Che and Fidel were having issues when Che gave his speech in Algeria. Fidel was probably thinking that Che would probably destroy everything that he created. Che also seems to think this as he talks about the reasons for him going to Bolivia. Being the calculating person he is, Fidel probably worked out a deal with the CIA to send him to Bolivia.