Seif Bamporiki, Rwanda Opposition Figure, Killed in South Africa

In 2010, another member of the R.N.C., a former army chief named Faustin Kayumba Nyamwasa, was shot and wounded in Johannesburg.

The killings of Rwandan dissidents in South Africa had led to diplomatic strains between the two countries, including the expulsion of diplomats, before a thaw in relations under the current South African president, Cyril Ramaphosa.

Lunga Ngqengelele, a spokesman for South Africa’s Department of International Relations and Cooperation, said that South Africa and Rwanda continue to enjoy “good working relations.”

Of Mr. Bamporiki’s killing, Mr. Ngqengelele said, “We are being led by the police, and so far they have not indicated that this is a political killing.”

Beyond South Africa, Rwandan government critics have also been targeted elsewhere. In Kenya, a former minister was shot dead in 1998 months after he said he was afraid for his life. In Belgium, a former government official’s mangled body was found floating in a canal in 2005.

And last August, after an elaborate ruse that Mr. Kagame called “flawless,” Paul Rusesabagina, a government critic who was credited for saving 1,268 lives during the Rwandan genocide, was arrested and charged with terrorism. That case has drawn worldwide condemnation.

In the case of Mr. Bamporiki, the man who ostensibly lured him to his death had been calling him consistently for a week, insistent that he wanted to buy a bed from his shop, Mr. Mutabazi, the R.N.C. spokesman, said on Monday. Mr. Bamporiki was at a party conference in Johannesburg at the time, but did not suspect anything untoward, Mr. Mutabazi said.