NEW : Biological family of two is arriving from Canada . A vigil is planned next week on Zahra 's birthday . The year - old 's disappearance is being investigated as a homicide . The girl 's father is charged with obstruction of justice .
NEW : Biological mother of Zahra Baker arriving from Australia . A vigil is planned next week on Zahra 's birthday . The 10-year-old 's disappearance is being investigated as a homicide . The girl 's stepmother is charged with obstruction of justice .