Bucyibaruta, who died on Wednesday aged 79, was the highest-ranking Rwandan to have faced trial in France over the 1994 massacres in which an estimated 800,000 Tutsis and moderate Hutus died in 100 days of mass killings.
Bucyibaruta was found guilty in July 2022 of complicity in genocide and crimes against humanity over four massacres in the southern province of Gikongoro. He was handed a 20-year sentence.
The massacres, committed at a school in Murambi and the parishes of Cyanika and Kaduha, left some 75,000 people dead on April 21, 1994.
The court however acquitted him as the perpetrator of the killings.
Bucyibaruta — one of only a handful of Rwandans to go on trial in France over the genocide — had appealed the conviction against him and was released from prison pending a new trial.
"Despite his grave crimes, he lived a good life... without facing the full force of justice," Philibert Gakwenzire, chairman of the genocide survivors' group IBUKA, told AFP.
"We urge governments and courts to consider the rights and emotional wellbeing of genocide survivors in these cases."
Throughout the original trial, Bucyibaruta contested the accusations against him and downplayed his importance in the chain of command as well as the resources available to him to prevent the killings.
He repeatedly said he had been "overwhelmed by the events."
Bucyibaruta became prefect of the Gikongoro province, which was among the worst-affected regions by the genocide, in 1992.
He fled Rwanda at the end of the genocide, on July 23, 1994, and had lived in France since 1997.
France has been one of the top destinations for fugitives fleeing justice over the Rwandan slaughter.
A former Rwandan doctor, Sosthene Munyemana, 68, has been on trial since November 14 over his involvement in the 1994 massacres — the sixth such proceeding to be held in France.