"She died on the rooftop waiting for a helicopter," Dr. Ben deBoisblanc said in 2005, describing the aftermath of Hurricane Katrina. "I haven't spoken to her husband. I don't even know where he is. I don't even know if he knows she's dead." Twenty years ago, whole neighborhoods in Louisiana were submerged in murky water as desperate residents waited for rescue. #neworleans #hurricanekatrina #60minutes