South African authorities said that for now they were treating the case as a robbery, but the political allies of the man who was shot, Serge Ndayizeye, had their suspicions of an assassination.

The envoy, Luca Attanasio, and another victim, a Carabinieri officer, were traveling in a convoy of the United Nations peacekeeping mission in the African country.

The Treasury Department slapped sanctions on the Israeli billionaire Dan Gertler in 2017 for corruption in Africa. In Donald Trump’s final days in office, they were rolled back with no explanation.