Exactly 50 years ago, UN Secretary General Dag Hammarskjold died in a plane crash on a mission to prevent civil war in newly-independent Congo. Suspicions that the plane was shot down, never fully laid to rest, are now again on the rise.
Just after midnight on 18 September 1961, he was heading to negotiate a ceasefire in a mineral-rich breakaway region of Congo, where another of his peacekeeping missions was getting bogged down in the complex politics of decolonisation and Cold War rivalry.
But his DC6 aircraft crashed in darkness shortly before landing, in a forest near Ndola in Northern Rhodesia - now Zambia.