Gene Dewey, a former U.N. staffer dealing with refugees and current U.S. Assistant Secretary of State on Population, Refugees and Migration, said his fallen friend was "one of humanity's great captains" and spoke of the "numbing dimensions of our loss."
Vieira de Mello, 55, was killed Aug. 19 in a suicide truck bombing at the U.N. headquarters in Baghdad. Eighteen more U.N. staffers and at least four other people died in the blast, which injured more than a hundred.
"No God can encourage and accept such acts, but by killing our father for what he stood for, they simply made him live on," said his son, Laurent, 25, standing next to his 23-year-old brother Adrien as their mother sat in the front row.
An honor guard of U.N. security police stood at attention throughout the service. The flower-bedecked coffin was carried by Vieira de Mello's six bodyguards.
Mourners recalled Vieira de Mello's life from his childhood in Brazil to his student days in Europe and his 34 years of service as one of the United Nations' top troubleshooters.
"Sergio's great adventure was to tell people that there are other things in the world than hate and despair," said Jose Flavio Silveira of Brazil, who studied with Vieira de Mello in Switzerland and France in the 1960s and toured with him behind the Iron Curtain.
Twenty-two candles burned to symbolize the other victims of the Baghdad bombing, and the family lighted another for Vieira de Mello.
David Lambo, an official of the U.N. High Commissioner for Refugees, said "his passing has left a big vacuum at the United Nations. He was truly one of the most charismatic personalities I've ever known."
After three decades working in some of the world's toughest hotspots, Vieira de Mello had been talked about as a possible future secretary-general of the United Nations.
He was close to Secretary-General Kofi Annan. During a wake last weekend in Vieira de Mello's native Brazil, Annan said he would "shine forever among our brightest stars."
Annan did not attend the Geneva funeral, but his wife, Nane, did. Also attending were American-born opera singer Barbara Hendricks, a friend of Vieira de Mello's and UNHCR goodwill ambassador; and East Timor Foreign Minister Jose Ramos Horta, the Nobel laureate who worked with Vieira de Mello when his country gained independence from Indonesia.
The service ended with the playing of John Lennon's "Imagine" as everyone held hands.
Vieira de Mello began his career with the office of the Geneva-based U.N. High Commissioner for Refugees in 1969. Over his career, he worked resolve conflicts or rebuild in the aftermath of wars in Mozambique, Cambodia, Bosnia, East Timor and elsewhere.
Last year, he was appointed U.N. high commissioner for human rights, also based in Geneva. At Annan's request, he took a leave of absence from that job in June for his four-month mission as the top U.N. envoy in Baghdad.
Vieira de Mello's funeral was originally set for Thonon-les-Bains, a nearby French town where he lived. But athorities invited the family to bury him in the Geneva cemetery, which is reserved for figures who have marked Swiss or international history.