The UN has called for an international investigation into the death of Muammar Gaddafi, the deposed Libayn leader, saying it could well have been a war crime. <br /><br />Christof Heyns, the UN Special Rapporteur on extrajudicial, summary or arbitrary executions, told Al Jazeera that a proper investigation into the exact events surrounding Gaddafi's death was a key test for Libya's future as a democratic and accountable state.