Jean Kambanda
As the fifth Prime Minister of Rwanda, he was instrumental in the Rwandan genocide of 1994 that saw the death of at least half a million people.
Kambanda not only distributed arms and ammunition to members of political parties, militias and the population, he also oversaw the setting up of road-blocks to identify the Tutsi and moderate Hutu, and eliminate them. Because of his inaction, child survivors of the massacre who were in the hospital were killed.
He became the first head of government to plead guilty to genocide. He is currently serving a life sentence in Mali.