The new head of the UN commission into the assassination of former Prime Minister Rafik Hariri arrived in Lebanon on Thursday, pledging to be impartial in an investigation that has divided Lebanese people and heightened tension between Syria and the United States. Serge Brammertz, a Belgian who was a deputy prosecutor at the International Criminal Court, takes over from Detlev Mehlis, who stepped down last month to return to his job as a senior prosecutor in Germany. The commission has implicated the Lebanese and Syrian intelligence services in the killing of Hariri, who was slain with 20 other people in a truck bombing in central Beirut on Feb. 14. While Lebanon praised the commission's interim reports, Syria rejected its findings and tried to discredit its witnesses. "I am actually aware of the expectations on the part of the families of the victims, the people of Lebanon and the international community, and I will do my utmost to meet these expectations," Brammertz said on arrival, according to a statement issued by the United Nations.