The spokesman for leading Rwandan opposition politician Victoire Ingabire has been found dead, a government official said on Sunday.
It was not immediately clear how 30-year-old Anselme Mutuyimana had died.
Rwandan President Paul Kagame has faced mounting criticism for what human rights groups say are widespread abuses, a muzzling of independent media, and suppression of political opposition. He denies those charges.
Several dissidents have been found dead inside Rwanda and in exile in unsolved cases in recent years.
Rwandan authorities said they were investigating the death.
“The investigation has started. No suspects so far,” said the spokesman for the Rwanda Investigation Bureau, Modeste Mbabazi.
Mutuyimana’s elder brother Augustin Tubanambazi said that the body had no visible wounds, but had blood in its mouth.
In 2010, the Democratic Green Party’s vice president, Andre Kagwa Rwisereka, was found dead.
In 2014, exiled former Rwandan intelligence chief Patrick Karegeya was found murdered in a Johannesburg hotel room while another former Rwandan senior officer Gen Kayumba Nyamwasa has survived four assassination attempts.
Ingabire, who returned from the Netherlands to contest a presidential election in 2010, had previously served six years of a 15-year sentence for inciting insurrection.
She said another official from her FDU-Inkingi party, Jean Damascene Habarugira, had been found dead two years ago and the crime had never been solved.
“We need justice,” Ingabire said.
She said witnesses had described men in police uniforms in a red car detaining Mutuyimana in the western Mahoko area.
Police did not return calls seeking comment on that report.