Rwandan President Paul Kagame, in a rare interview, is asked to respond to allegations by a French investigating judge that he was complicit in the assassination of former President Juvenal Habyarimana in 1994. BBC world affairs correspondent Fergal Keane reports.
At the time of the genocide, most observers believed President Habyarimana had been killed by Hutu extremists opposed to his peace deal with the Tutsi-dominated Rwandan Patriotic Front (RPF).
But French judge Jean-Louis Bruguiere alleges that the RPF leader Paul Kagame - now Rwanda's president - ordered the attack in order to seize total power.
The fact that it is a French judge making the allegation has made this a politically explosive issue.
The French armed and trained the extremists who would later go on to carry out the genocide.
I have spoken with several of Judge Bruguiere's witnesses.
They are men who at one time fought alongside Mr Kagame but have since turned against him.
Innocent Marara said he was based at Mr Kagame's headquarters at the time of the shooting down of the plane.
He claims to have overheard the RPF leader discuss the attack on several occasions.
Mr Marara said Mr Kagame was "collecting advice from people around him" on the president and the plane attack.
I asked what choice Mr Kagame made in the end.
"That was the shooting," Mr Marara said. You are absolutely sure about that, I asked. "Yes."
The Rwandan government accuses Mr Marara of making up the story and says he was involved in criminal gangs. He denies the allegations.
Another witness is Paul Kagame's former defence minister, Emmanuel Habyarimana, now living in exile in Europe.
The genocide followed the shooting down of the president's plane
Emmanuel Habyarimana was once an officer in the Hutu army but defected to the RPF in 1994.
He subsequently fled from Rwanda after falling out with the ruling party.
He told me the Hutu army did not have the missiles to shoot down the plane.
And he claimed he had heard senior RPF officers boasting about having shot down the plane.
"The members of the army - especially officers - didn't hide that they would have had to bring down the plane to take power. They said it loud and clear. They were even proud of shooting down the plane."
In response, the Rwandan government accuses Emmanuel Habyarimana of being a deserter and says he has a political axe to grind as a leader of an opposition party in exile.
I travelled to Rwanda to put Judge Bruguiere's central allegations to President Kagame.
In a defiant response he said: "I care that there was a genocide here. A million people died - people have been persecuted for decades here in Rwanda.
Bruguiere says Mr Kagame ordered the plane shot down
"I was a refugee for nearly 30 years out of my country as a result of that. Would I care that bloody Habyarimana died, somebody who was responsible for a genocide here, who was a president of a government that discriminated, that persecuted its own people?
"That Judge Bruguiere says this or France says that - I don't give a damn."
In the aftermath of the genocide, the UN backed away from an investigation of the plane crash.
One investigator alleged the matter was dropped because the UN did not want to confront Paul Kagame.
But could the Bruguiere report provide the evidence for an indictment of Paul Kagame?
The former chief prosecutor for Yugoslavia and Rwanda, Judge Richard Goldstone, thinks not.
"Well I don't think that case has been made at all. It's a very political judgement and I don't believe that it's borne out by the evidence.
"Certainly the witnesses who spoke to Bruguiere allege that those were statements made by President Kagame himself. Whether he did or not obviously is a matter in dispute, in hot dispute, but the political judgement it seems to me is another matter."
However, in his interview with the BBC, Mr Kagame said he would co-operate with an impartial inquiry carried out by a judge who had nothing to do with Rwanda or France.
Whether any judge would want to take on such a task is quite another matter.