[1] He was the issue of an ancient Belgian noble family and grew up at the castle of Ottignies [fr].

Initially, Kestergat reported on domestic Belgian matters, until he undertook his first foreign mission in 1957.

The next year, he reported on the Belgian Congo for the first time, which would become his main subject for the rest of his career.

Jean Kestergat was the author of several novels, a biography of André Ryckmans [nl], as well as several works of journalism and contemporary history, namely on the politics of the Democratic Republic of the Congo.

Together with Jacques Brassinne de La Buissière, who wrote his doctoral dissertation on the murder of the first Congolese Prime Minister Patrice Lumumba, he wrote Qui a tué Patrice Lumumba?