Opposition leaders in Ottawa and Nova Scotia are calling for further investigation into why the RCMP destroyed potential evidence in the criminal proceedings against a Halifax man who was wrongfully convicted of murder.

Federal NDP Leader Jagmeet Singh says an outside probe is needed to examine why RCMP destroyed an investigator's research on other suspects in the lead-up to Glen Assoun's unsuccessful 2006 appeal.

He calls techniques employed by police in the case "very concerning" and says they raise questions about how fairly accused are treated in our criminal justice system.