Former hotel driver Claude Muhayimana goes on trial in Paris today (November 22) accused of complicity in Rwanda's 1994 genocide by transporting Hutu militiamen who massacred hundreds of Tutsis.
Muhayimana, 60, who investigators say also hid Tutsis at risk of death and helped some escape, fled after the genocide and gained French nationality in 2010.
Around 50 witnesses are expected to testify at what will be the third trial linked to one of the worst tragedies of the 20th century.
The genocide saw 800,000 minority Tutsis and moderate members of the Hutu majority slaughtered in just three months from April to July 1994.
At the time, Muhayimana was a driver for the hotel Guest House in Kibuye, on the shores of Lake Kivu.
He is accused of "complicity" in genocide and crimes against humanity for having "aided and abetted" the militia by transporting them on several occasions to the sites of massacres in the western Kimberley region, where tens of thousands of people were killed.
Muhayimana faces a life sentence if convicted. He was arrested in 2014, a year after the opening of an investigation initiated by a complaint from the Collective of Civil Parties for Rwanda (CPCR), which fights against impunity and the presence in France of those allegedly involved in the Rwandan genocide.
Three people have already been convicted: an army officer sentenced to 25 years in prison, and two mayors who were given life sentences.
But Muhayimana will be the first "ordinary" citizen to face justice having been considered "respectable all-around" before the killings, said Alexandre Kiabski, a lawyer for the CPCR, one of the plaintiffs.
He dismissed claims by the defence that Muhayimana had no choice but to obey the Hutu authorities, saying "there were other drivers who refused".
The trial will last nearly a month, hearing dozens of witnesses, including 15 from Rwanda.
"We are dealing with an ordinary citizen who had no authority over anyone," said Philippe Meilhac, one of the accused's lawyers.
"He will explain himself in length, breadth, and depth. He is a man who has been waiting for 10 years."
France has for years denied requests to extradite suspects to Rwanda, fuelling a row between the two nations, with President Paul Kagame accusing Paris of denying Rwanda jurisdiction.
But relations between the two countries have warmed considerably since a historians' report commissioned by President Emmanuel Macron and released in March recognised France's "overwhelming" responsibilities in failing to halt the massacres.
Macron also visited Kigali in May, when he acknowledged that his country had ignored warnings of the impending massacres while backing the genocidal regime.
Around 30 trials of other Rwanda genocide suspects remain to be heard by French courts.