The case of Laurent Bucyibaruta is the fourth that came to the court in relation to a genocide that killed an estimated 800,000 Tutsis in 1994.
A former senior Rwandan official goes on trial in Paris accused of complicity in the African nation's genocide, the most senior figure yet to face justice in France over the 1994 massacres.
Standing trial of Laurent Bucyibaruta on charges of genocide, complicity in genocide and complicity in crimes against humanity, the 78-year-old ex-official faces a life sentence if convicted on Monday.
At the heart of the case are several "security" meetings, either ordered by Bucyibaruta or in which he participated. The accusation says they were slaughter-planning sessions.
The case of Bucyibaruta is the fourth from the genocide to come to court in France, which had long been under pressure from activists to act against suspected perpetrators who had taken refuge on French soil.
In particular, the former prefect of the southern province of Gikongoro is accused of persuading thousands of people to take refuge in the Murambi Technical School, by promising them food and water — and protection.
But days later, in the early hours of April 21, tens of thousands of Tutsis were executed in one of the genocide's grimmest episodes.
An estimated 800,000 Tutsis and moderate Hutus perished in 100 days of slaughter in 1994 in which Hutu militiamen massacred Tutsis taking cover in churches and schools.
Massacre of around 90 Tutsi pupils
The court will also discuss Bucyibaruta's responsibility in the massacre of around 90 Tutsi pupils at the Marie Merci school in Kibeho on May 7 and in the execution of Tutsi prisoners — including three priests — in Gikongoro prison.
Bucyibaruta denies the charges and refutes any involvement in the killings.
His lawyers will first call for the case to be thrown out for unreasonable delays, as the proceedings began 22 years ago.
But if that fails, Bucyibaruta's defence told AFP news agency they would call for his acquittal.
The trial is expected to last two months and feature over 100 witnesses including survivors from Rwanda, who have flown over or will appear via videoconference.
Bucyibaruta, who has been in France since 1997 and is under judicial supervision, has a myriad of health problems which should limit the hearings to seven hours a day.
Four people in three cases have already been convicted in French courts over the genocide: a former hotel driver handed a 14-year sentence, an army officer sentenced to 25 years in prison, and two mayors who were given life sentences.