stockholm swedish prosecutors accuse democratic republic congo government wednesday cooperate investigation murder u.n. sanction monitor sweden zaida catalan american colleague michael sharp shoot dead march find shallow grave area central congo gather information conflict army militia congo government arrest dozen people connection kill blame militia though one report u.n. security council suggest state security service could also involve swedish prosecution authority launch investigation catalan death say wednesday receive response request make april information congolese authorities swedish investigation face severe difficulties give fact completely reliant evidence exist congo cooperation work congo prosecutor sara nilsson say statement material swedish authorities manage collect exclude persons close tie regime congo involve murder authority add april congo government screen video reporters say show members militia kill catalan sharp analysts say grainy footage raise question answer nilsson tell reuters screen taint important evidence congo government spokesman lambert mende deny congolese officials involve murder say wednesday swedish authorities provide information congolese court hear case way around justice render crime commit mende say information court might able access give court conflict kasai region congo army kamuina nsapu militia kill many 5,000 people displace around 1.5 million since august last year unite nations repeatedly accuse congolese force use excessive force target civilians allege tie militia government deny charge sweden say congo help investigation murder u.n. monitor