[3] Born to a Hutu family in Gitarama, Mpiranya was a major in the Rwandan Armed Forces at the time of the war and commanded the Presidential Guard.

Many more government officials, such as Faustin Rucogoza, were murdered by Mpiranya before he and his forces embarked on the genocide of hundreds of thousands of ethnic Tutsi and moderate Hutu civilians.

His whereabouts remained unknown, but in 2012, under pressure from Kigali, the Zimbabwean government admitted that he could possibly be at large in the country, and promised to find him "dead or alive".

[7] The ICTR indictment alleges that between 1990 and 1994, Mpiranya and other officers conspired to exterminate the Tutsi civilians and political opponents, and helped to train interahamwe and militia groups who committed the genocide.

[7] On 5 January 1994, the day that the Broad-Based Transitional Government specified by the Arusha Accords was to be sworn in, Mpiranya prevented the access of political opponents onto the premises of the Conseil national de développement, particularly Lando Ndasingwa and his Liberal Party.

[7] After Habyarimana's death and the start of the genocide, members of the Presidential Guard presumedly led by Mpiranya[citation needed] "tracked down, arrested and killed" Rwandan Prime Minister Agathe Uwilingiyimana.

[11][12] In February 2010, Mpiranya was reported by Belgian authorities to be sheltered by the Zimbabwean government, operating businesses in Harare, on top of acting as mercenary for the ruling party ZANU-PF to silence the opposition.

[13][14][15] In August 2010, Rwanda appealed for United Nations intervention in its diplomatic row after the Zimbabwean government refused to extradite Protais Mpiranya to the ICTR.

Security sources said that the Harare authorities were not keen on giving up the fugitive to whom they feel indebted over his reconnaissance role during the 1998–2001 Democratic Republic of Congo civil war.

[20] In April 2022, Mpiranya's body, conclusively identified by DNA testing, was exhumed from a grave in Harare, Zimbabwe at the request of UN investigators; it had been buried under the name "Sambao Ndume".