A high-ranking civil servant, Barayagwiza served as policy director within the Ministry of Foreign Affairs at the time of the Rwandan genocide.

[5] Barayagwiza was a founding member of the extremist party Coalition for the Defence of the Republic, which was considered to take an even more radical stance against the Tutsi population than the governing National Republican Movement for Democracy and Development.

[5] On 23 October 2000 he was charged by the International Criminal Tribunal for Rwanda with Genocide, Crimes Against Humanity and violations of the Geneva Conventions.

He announced that he was appealing the sentence and was assigned Donald Herbert and Tanoo Mylvaganam as a new defence counsel on 30 November 2004.

[8] He died on 25 April 2010 in Porto Novo, Benin,[6] due to an advanced case of Hepatitis C. It has been reported by his family that he was denied adequate treatment.