He supported Prince Louis Rwagasore and was a member of his political party, the Union for National Progress (UPRONA).

[5] National elections were held and won by UPRONA;[6] Ngendandumwe became the only member of the Legislative Assembly to hold a university degree.

[1] In December Belgian Foreign Minister Paul-Henri Spaak summoned Rwandan and Burundian representatives to Brussels to discuss the future of their territory.

[15] He served as part of a Burundian delegation sent to the United Nations Headquarters in February to finalise the terms of Burundi's independence.

[20] Upon swearing in he announced a programme for "bread and peace", including an initiative to preserve coffee trees and an appeal to all citizens to provide two days of free labor to the country to bolster the state treasury.

[21] From this point onward the Mwami exerted considerable control over Burundian politics and made the cabinet responsible to him instead of Parliament.

The appointment was protested by the Tutsi-dominated Rwagosore National Youth, the Federation of Burundian Workers, and the Union of Administration Agents.

The Hutu-dominated Party of the People (PP), bolstered by UPRONA defections, saw a political opportunity and billed itself as a champion of the Monrovia group's ideas, renaming its youth wing the Jeunesse Populaire Ngendandumwe.

[b] UPRONA loyalist civil servants denounced the youth organisation as a group founded to "avenge" the late prime minister.

The man accused of killing Ngendandumwe was Gonzalve Muyenzi, a Rwandan refugee who worked at the United States Embassy.

Shortly after the murder several Rwandan refugees were arrested, including most of the leaders of the Armée Populaire de Libération Rwandaise.

[39] The police detained a man named Butera, another employee at the United States Embassy and the son of François Rukeba, a prominent Rwandan exile rebel leader.

A ballistics expert alleged that the bullet which killed Ngendandumwe had been traced to a gun found in the possession of Butera.

[41] In December 1967 the Supreme Court of Burundi, citing lack of evidence, dismissed all charges against those accused in the murder.