Félicien Kabuga, 89, refused to show up to court at The Hague, with his defence team citing health concerns. Doctors say he is fit to stand but only for two hours a day.
But it was still a day of huge significance for millions of Rwandans who survived machete-wielding gangs during the 100-day massacre in 1994 which left some 800,000 people dead.
"Twenty-eight years after the events, this trial is about holding Félicien Kabuga to account for his substantial and intentional role in that genocide," prosecutor Rashid S Rashid told the United Nations tribunal.
Prosecutors are settling down for a mammoth process. Former business tycoon Mr Kabuga has pleaded not guilty to accusations of genocide, incitement to commit genocide, conspiracy to commit genocide, persecution, extermination and murder.
If convicted, he faces a maximum sentence of life imprisonment.
Much of the case revolves around his use of a radio station to incite hatred and enable mass murders, as well as his arming of Hutu militias that hunted down Tutsis.
In 1992, Mr Kabuga funded Radio Television Libres Milles Collines (RTLM), a radio station that poured out venom towards the country's Tutsi minority.
The following year, he allegedly began to import hundreds of thousands of machetes which were given to the Interahamwe, a Hutu militia accused of overseeing much of the slaughter.
The mass killing of Rwanda's Tutsi minority was triggered on April 6 1994, when a plane carrying president Juvénal Habyarimana was shot down and crashed in the capital Kigali.
Mr Habyarimana, who came from the ethnic majority Hutu group, was killed.
The Tutsi minority was blamed for downing the plane. Bands of Hutu extremists began slaughtering Tutsis and their perceived supporters with help from the army, police and militias.
Mr Kabuga’s radio station often provided the locations of hiding Tutsis so they could be hunted down and killed. His daughter was married to Mr Habyarimana's son.
"RTLM broadcasts glorified this violence, celebrating killings, praising killers and encouraging perpetrators to continue the violence at roadblocks and other locations," says the 15-page indictment against Mr Kabuga.
It also accuses him of arming and supporting Hutu extremist Interahamwe militias, including one unit known as "Kabuga's Interahamwe".
When the horrors finally ended 100 days later, Mr Kabuga went on the run
The US put a $5 million bounty on his head, but thanks to powerful political connections in East Africa and bountiful cash from his dealings in tea and coffee he kept slipping away, reportedly using fake passports to criss-cross continents.
Kenyan journalists and investigators who tracked him down ended up murdered.
Eventually French police arrested him in a flat on the outskirts of Paris in 2020. UN prosecutors said that British security services played an "essential" role in the operation to find him.
"Even with money and protection, one cannot escape a genocide crime," Naphtal Ahishakiye, from the genocide survivors’ group Ibuka, said.