The UN chief has appointed a former Canadian prosecutor to head a commission investigating the 2005 assassination of former Lebanese premier Rafik Hariri, according to a letter to the Security Council released Tuesday. Daniel Bellemare replaced Belgian lawyer Serge Brammertz, who was nominated to head the Yugoslav war crimes tribunal in the Hague. Secretary-General Ban Ki-Moon made both announcements in two letters to the Security Council, which must approve the Brammertz appointment. In a July report, Brammertz signaled that the UN International Independent Investigation Commission would wrap up its work and transfer findings to the international tribunal established by the Security Council on May 30 to prosecute suspects in Hariri's assassination. Brammertz said the UN inquiry had identified people who may have been involved, though he did not name anyone. He said investigators had "significantly narrowed down" possible motives for the slaying to Hariri's political and personal relationships in Lebanon, Syria and other countries. The first UN chief investigator, Germany's Detlev Mehlis, had said the plot's complexity suggested that Syrian and Lebanese intelligence services had a role. Four pro-Syrian Lebanese generals have been under arrest for alleged involvement in the murder. International pressure and huge protests in Lebanon following Hariri's assassination prompted Syria to pull its troops out of Lebanon after a 29-year presence. Syria has denied involvement in the murder. Bellemare was Canada's assistant deputy attorney general until from 1993 until December 2006, overseeing federal prosecutions in the country. He later became special advisor to Canada's deputy minister of justice until he retired from public service in September, according to a resume attached to Ban's letter. Before heading the Hariri probe, Brammertz was deputy prosecutor of the International Criminal Court in the Hague. But his nomination to succeed Carla Del Ponte as chief prosecutor at the Yugoslav war crimes tribunal came despite objections from 12 human rights groups in Yugoslavia and 18 senior lawyers, including trial attorneys. In two separate letters to Ban, the lawyers and rights activists backed del Ponte's deputy, American David Tolbert, arguing that a newcomer could disrupt the International Tribunal for the Former Yugoslavia in its final years. The Security Council, which created the court in response to atrocities committed as the former Yugoslavia disintegrated in a series of wars, has urged the tribunal to complete its work by 2010. Four key suspects remain at large, including former Bosnian Serb leader Radovan Karadzic and his military chief, Gen. Ratko Mladic, both charged with genocide. Trials for others are expected to take months to complete and are yet to start. Kelly Askin, an international law expert at the Open Society Justice Initiative and a former adviser to judges at the Yugoslav and Rwanda tribunals, warned last month that naming an outsider as chief prosecutor could lead to an exodus of senior trial and appeals staff. But Tolbert's nationality may have worked against him. US support for the independence of Kosovo has strained relations with Serbia, and there are worries that could undermine an American's ability to press the Serbian government to arrest and hand over fugitives.