An 88-year-old man accused of being a major financier of the 1994 Rwandan genocide is unfit to stand trial, a UN court has ruled.
Félicien Kabuga's lawyers had argued that he suffered from dementia.
He was arrested in Paris in 2020 after evading capture for 26 years, reportedly moving around East Africa.
He is alleged to have financed ethnic Hutu militias who slaughtered about 800,000 Tutsis and moderate Hutus. He has denied the charges.
This is the first time a court has given such a ruling in a decades-long campaign to bring Rwandan genocide suspects to justice.
In their ruling, judges at a UN war crimes court in The Hague said Mr Kabuga was "unfit to participate meaningfully in his trial and is very unlikely to regain fitness in the future".
The judges proposed an alternative legal procedure that "resembles a trial as closely as possible, but without the possibility of a conviction".
The court had paused his trial in March to allow for his health to be assessed. According to court documents, he is 88, although there is some dispute about his precise age.
It is alleged that Mr Kabuga used his large fortune, made in the 1970s tea trade, to buy weapons used to arm the Hutu death squads.
The wealthy businessman is also accused of using his radio station to urge Hutus to kill Tutsis, fuelling the genocide by broadcasting inflammatory hate speech.
French investigators tracked him down to an apartment in Paris where he had been living under a false identity.
The United States had offered a reward of $5m (£4.1m) for information leading to his arrest.