Accountability for missing persons is 'crucial': UN human rights chief / 'Missteps' in American college student disappearance probe have permanent consequences: retired FBI agent / Investigators weighing all options in search for missing American college student / Missing woman at centre of murder inquiry named / Missing woman search becomes murder inquiry / Missing persons issue a big challenge, law minister tells Senate / Cabinet body seeks comprehensive report on missing persons / Google Street View image may offer clue into case of missing woman / It is responsibility of state to trace missing persons: SHC / Native American families remain frustrated with unsolved missing persons, killings cases