"Members of the government have made contradictory statements about the motives and identity of this leading journalist’s murderers," RSF said.
"We urge President (Mahinda) Rajapakse to assign members of the criminal investigation police to the case and to formally request the help of international experts in solving the murder."
Wickrematunga was a member of the majority Sinhalese community but was fiercely critical of government policy, especially its bloody and costly war against Tamil rebels.
RSF said there was no "political will to resolve the case," leaving Wickrematunga's family and colleagues to believe that the authorities have no interest in arresting the perpetrators or the instigators.
Police have arrested a suspect who stole Wickrematunga’s mobi