All previous official comments have insisted that the crash was an accident. Mr Garang was travelling in Mr Museveni’s helicopter when he died.
“Some people say accident, it may be an accident, it may be something else,” he said in Yei, one of the southern towns where Mr Garang’s body is being taken before the funeral on Saturday.
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Mr Garang died three weeks after being named vice-president as part of a deal to end 21 years of civil war.