Rwanda's former intelligence chief faces genocide and war crimes charges as his trial begins in France for a 1994 killing spree that left at least a half-million people dead.
Pascal Simbikangwa, 54, could face a life sentence if convicted after the seven-week trial - the first in France over Rwanda's genocide.
The case has highlighted criticism of France's own reaction to the genocide a generation ago, and its slow exercise of justice after the slaughter of at least 500,000 people in Rwanda in just over 100 days.
"We'll do what we have done from the start, plead for a not-guilty verdict," said defence lawyer Fabrice Epstein, claiming the facts haven't fully been established.
The defendant, infirm from an accident years ago, was wheeled into the courtroom then transferred to a glassed-in area. He identified himself as "Pascal Safari", a combination of his real name and his alias, Senyamuhara Safari, according to court documents.
More than 50 witnesses - including journalists, historians, farmers, security guards and intelligence officials - are expected to be called to testify, nearly all by the prosecution. Among civil parties to the case are Alain Gauthier and wife Dafroza, who lost more than 80 family members in the genocide.
"I am especially dedicating this (trial) to the anonymous victims of Pascal Simbikangwa, those without a name, a grave," she said before the start of the trial. "This is for them today. We are thinking of them."
Simbikangwa's defence team has expressed concern that the trial will be lopsided - in part because of the difficulty in finding witnesses who will speak out in his defence.
Several films are to be shown at the trial, including "Kill Them All" - a 2004 documentary on the genocide.
France had close ties to the government of Rwandan president Juvenal Habyarimana, an ethnic Hutu who was killed when his plane was shot down in 1994. His death set off a torrent of reprisal slayings of ethnic Tutsis and moderate Hutus, in what has been called the 20th century's fastest genocide.
An array of civil parties to the case say Simbikangwa, who came from the same town as Habyarimana and was allegedly a relative, was in the president's inner circle. From at least one roadway checkpoint in Kigali, he is alleged to have incited the army to identify and slaughter Tutsis.
Critics say France was slow to react to the slaughter. Before the killings, French troops had armed and trained the Rwandan army and during the genocide, they allegedly helped radical Hutus flee the country. Later, France took in a number of exiles who have lived for years free from prosecution.
A French trait for "ill-founded self-certainties" that engulfed "the administration, the army and the diplomatic corps" was to blame, according to French former foreign minister Bernard Kouchner, who made repeated trips to Rwanda during the genocide as a humanitarian aid activist.
"Today's trial in Paris ... will be an important moment in the global fight against impunity," Leslie Haskell, the international justice counsel for Human Rights Watch, said in a statement. He noted the creation of a special war crimes unit in the French justice system in 2012.
"France now has the tools it needs to ensure (that) perpetrators of the world's most serious crimes don't escape justice or find a safe haven in the country," Haskell said.
The trial could be the first of many. Another 27 cases linked to Rwanda's genocide are being investigated in the Paris court's war crimes unit, including one focusing on Habyarimana's widow.
The UN tribunal on the Rwanda genocide and several Western countries - including Belgium, a former colonial overseer of the African country - have brought scores of Rwandans to justice. The UN International Criminal Tribunal in Arusha, Tanzania, will close later this year, and is now only hearing appeals, officials say.