Authorities in the Democratic Republic of Congo say the main suspect is still at large.
Two people have been arrested in the Democratic Republic of Congo over the killing of Italian ambassador Luca Attanasio and two others.
Police in the eastern province of North Kivu announced the arrests on Tuesday but said that the main suspect -- referred to as "Aspirant" -- remains at large.
General Aba Van Ang said that rebels had killed Attanasio in February 2021 in a botched attempt to kidnap him for ransom.
The 43-year-old was fatally shot during an ambush, along with paramilitary officer Vittorio Iacovacci and a UN World Food Programme (WFP) driver, Moustapha Milambo.
The convoy was traveling from Goma to Rutshuru, where the ambassador was to visit a WFP project feeding students at a school.
On Tuesday, police also presented four other men accused of attacking other humanitarian workers in the region.
Italy has formally asked for an inquiry into what happened amid questions about whether UN security arrangements were sufficient for the mission.
The United Nations has said the road had been cleared for travel without security escorts or armoured vehicles.