AUSTIN, Texas -- Police in Austin were still trying to determine Tuesday what happened to a woman and her newborn who were reported missing last week.Heidi Broussard, 33, and her daughter, Margot Carey, who was born Nov. 26, were reported missing Thursday evening. Police say the two were last seen as Broussard dropped off a child at an elementary school that morning. Broussard and the baby are believed to have returned to their apartment but haven't been seen since.Police Detective Brad Herries said authorities are exploring "every possibility" and at this point are assuming they are alive."It's possible that Heidi and Margot have left on their own accord," Herries said. "It's also possible that there may be something nefarious or foul play involved."He said police do not have a person of interest in the case.