Anti-terrorism prosecutors said Saturday that a preliminary investigation was opened after Ntiwiragabo was found hiding in the suburbs of the city of Orleans, about 100 kilometres south-west of Paris.
French investigative news site Mediapart tracked down the former Rwandan spy chief, who was identified by the International Criminal Tribunal for Rwanda (ICTR) as one of the architects of the genocide.
Neither the ICTR, Interpol, France nor Rwanda were actively seeking him now and had dropped arrest warrants years ago.
The revelation of his whereabouts comes barely two months after another suspected genocide architect, Felicien Kabuga, was arrested on the fringes of Paris.
Kabuga, who evaded police in several countries for 25 years, is accused of financing the genocide.
Kabuga had asked for a trial in France, citing frail health and claiming the United Nations court in Africa would be biased against him, and possibly hand him over to Rwandan authorities.
France has long been known as a hiding place for wanted genocide suspects and French investigators currently have dozens of cases underway.
A plane carrying President Juvenal Habyarimana, from Rwanda's Hutu majority, was shot down in Kigali on April 6, 1994, unleashing the killing spree that would leave mainly Tutsis but also moderate Hutus dead.
(AFP)
