GENEVA — For more than two years, critics of President Pierre Nkurunziza of Burundi and independent activists have fallen victim to homicide, have disappeared into secret detention centers or escaped to neighboring countries, recounting torture and rape at the hands of the military and the police.

Now, United Nations human rights investigators say they believe Burundi’s top leaders and state security agencies committed crimes against humanity.

A panel of investigators set up by the United Nations Human Rights Council a year ago said on Monday that it delivered a list of suspects to the United Nations High Commissioner for Human Rights and was giving the Security Council another list of people it said should face sanctions. It urged the International Criminal Court to open an inquiry.

As the panel prepares to present its findings this month to the 47-member Human Rights Council, which includes Burundi, its report also raises questions about whether the country should be allowed to remain on the council.