A pro-Israel rights group filed a complaint Monday against the head of a UN investigation into systematic abuses in Israel and the Palestinian territories for prejudice, demanding she resign. Navi Pillay, a former United Nations High Commissioner for Human Rights, was appointed last July to head a high-level probe into “all underlying root causes” in the drawn-out conflict. UN Watch, a Geneva-based rights group that monitors UN activities, said the South African jurist had displayed “demonstrable bias against Israel, including on issues specifically related to the case and controversy that is …