Millionaire's girlfriend found hanged in series of intricate knots. Murder or suicide?

The mystery of how Rebecca Zahau was hanged off the balcony of her boyfriend's Southern California mansion was investigated by police and the subject of a wrongful death lawsuit -- but the truth is still evasive. Investigators initially concluded the 32-year-old killed herself days after her boyfriend's son suffered a fatal fall in the same home, but a jury recently decided the boyfriend's brother was legally responsible for her death. Nancy Grace digs into the case with famed forensic pathologist Cyril Wecht, who investigated it for the civil lawsuit and Zahau family lawyer Keith Greer, who won a $5 million judgment against Adam Shacknai, the man who called 911 to report finding Zahau dead. They are also joined by Seattle lawyer Anne Bremner, forensics expert Joseph Scott Morgan, Dr. Carole Lieberman -- author of "Lions, Tigers & Terrorists, Oh My! How to protect your child in a time of terror," and Crime Stories contributing reporter Ninette Sosa.