Operating in Venezuela during the 1990s, Vargas was convicted of multiple murders and the consumption of his victims' remains, crimes that drew sustained national attention and earned him one of the more explicit nicknames in the catalog of documented serial killers. The case raised difficult questions about the failures of social and psychiatric systems that had prior contact with him before his arrest.

Operating as an informant and agent for the German occupation forces, Rinnan built a network that penetrated Norwegian resistance cells through infiltration and deception, leading to the capture, torture, and death of scores of his own countrymen. The scale of betrayal he orchestrated from within made him one of the most damaging collaborators of the occupation period.