UN May Look Into 'Great Political Mystery' of 1960s What happened in plane crash that killed Dag Hammarskjold? By Jenn Gidman, Newser Staff Posted Dec 15, 2014 9:58 AM CST 1 comment Comments This May 19, 1953, file photo shows Dag Hammarskjold, recently appointed secretary-general of the United Nations, on a visit to Sweden smoking his pipe at a press conference held in Stockholm. (AP Photo) (Newser) – For more than 50 years, the death of Swedish diplomat Dag Hammarskjold has remained one of the era's biggest mysteries. The UN secretary-general's plane plummeted out of the skies in September 1961 in Northern Rhodesia (now Zambia) as he flew to orchestrate a ceasefire between Congo's government and Katanga province separatists; a 1962 crash report pointed the finger at pilot error, the Guardian reports. But with new evidence reportedly on the table, including testimony from locals that had been previously swept under the rug, Sweden will today ask the UN to form an independent panel to assess the evidence. The panel would be able to appeal for NSA and CIA files on the crash, as well as classified documents from the UK and other countries. Rumors have run rampant since the crash, including one that claims a second plane had been near Hammarskjold's Albertina DC-6, the Observer notes. The acting security chief on Hammarskjold's plane—who died of his injuries a few days after the crash—reportedly told medical staff he had seen "sparks in the sky," while a Belgian pilot claimed he sent the Albertina crashing down by mistake after he fired warning shots at the plane's wing. Other witnesses insisted they saw the Albertina sprinkled with bullets and men in combat uniforms at the crash site, and there were whispers that Hammarskjold had been shot and was found on a termite mound with an ace of spades playing card on his collar. It didn't help stave off conspiracy theories when former President Harry Truman said the day after the crash that Hammarskjold "was on the point of getting something done when they killed him."