Incarcerated since his conviction in 2023, Munyemana was accused of signing a motion of support for the interim government established after the attack on the plane of Hutu President Juvénal Habyarimana, which was immediately followed by massacres.

That motion encouraged the genocide committed in Rwanda between April and July 1994, which left more than one million people dead, mostly ethnic Tutsis, along with moderate Hutus, according to the UN.

Sosthène Munyemana was also tried for setting up roadblocks and patrols in Tumba, a locality in the southern prefecture of Butare, where people were arrested then killed, and for holding the key to a district office where Tutsis were locked up before their execution.

He was a close associate of Jean Kambanda, Prime Minister in the interim government, who was sentenced in 2000 to life imprisonment by the International Criminal Tribunal for Rwanda (ICTR) for his participation in the genocide.

Munyemana arrived in September 1994 in France, where his wife was already living. The father of three children, he rebuilt his life in south-western France, working as an emergency doctor and then as a geriatrician.