She was found guilty of participation in the 1994 genocide.
The tribunal held Mwamina responsible of supervising roadblocks where people were killed in the Nyakabanda sector of Kigali, and of participating in the assassination of the Ruterana family in 1994.
Several witnesses testified that she carried a Kalashnikov assault rifle and a gun while inspecting the roadblocks. They also stated that she ran a roadside stand where killers used to have a drink after the massacres.
The convicted hails from ex-Ruhengeri prefecture (northern Rwanda). After the defeat of the old regime in July 1994, she fled to Zaire (today's Democratic Republic of the Congo), before returning to Rwanda in 1998. Until her arrest in 2008, she lived without attracting attention in her native region.
Last Sunday, another female militia leader, Shakila Uwingabire, was sentenced to life imprisonment. The latter, however, was condemned in absentia having fled Rwanda just prior to the opening of her trial.
The Gacaca courts, adapted from a form of Rwandan traditional justice, are tasked with trying suspected perpetrators of the 1994 Rwandan genocide which left some 800,000 people dead, according to the UN. These village courts, whose judges are elected from the community, can hand down sentences up to life imprisonment, which is now the maximum penalty in Rwanda. They have so far tried more than a million people.