Claver Berinkindi, who is of Rwandan origin and became a naturalized Swede in 2012, was accused of leading mobs in the clubbing, stabbing and shooting to death of thousands of men, women and children in Butare, southern Rwanda.
Stockholm District Court convicted him on Monday of genocide and gross violations of international law, including murder, attempted murder and kidnapping.
The court concluded that the man was a leader at a local level during the genocide, including involvement in the massacre of thousands of people at the Nyamure mountain, and an attack on a local government building in which hundreds lost their lives.
In a first for genocide trials in Swedish courts, compensation of between 30,000 kronor ($3640) and 100,000 kronor ($12,134) will be paid to 15 victims.
The defence attempted to challenge the sentence on the grounds that witness identification was unreliable due to the length of time passed since the incidents.
“There are differences in opinion among the testimonies regarding what can be recalled,” argued the 61-year-old’s defence lawyer Hanna Lindblom, who said her client would appeal.
The Court countered however that the testimonies had been carefully examined, and that humans generally recall traumatic memories well for a long period after the event. Chief prosecutor Tora Holst also noted that witnesses would prefer to forget traumatic incidents, but could not.
The trial, which began in September 2015, partly took place in Rwanda and involved over 50 witnesses gathered by the prosecution. It is only the second time a genocide trial has been held in Sweden, the other being when a Rwandese-Swedish man was sentenced to life in prison in June 2013.
According to the UN, around 800,000 people died in the Rwandan genocide, which began after the assassination of Rwanda's Hutu president Juvenal Habyarimana in 1994.