Swedish police arrested a 48-year-old man suspected of involvement in the 1994 genocide perpetrated against Tutsi, police and prosecutors said.
The man, whose identity was not revealed, was arrested at dawn on Tuesday in his house at Örebro, about 160 kilometres west of Stockholm.
The suspect went to Sweden in 1998 and was naturalized in 2006. He is suspected of genocide and gross violations of international law, said the prosecutor.
Sweden sentenced to life imprisonment two other naturalized Rwandans, Stanislas Mbanenande and Claver Berinkindi, in 2014 and 2016 respectively, for their roles in the genocide.