Siobhan McGuinness, 5, disappeared while walking home from a play date, just two blocks from her home. Her body was found four days later, stabbed to death and hidden in a drain culvert packed with snow. For more than four decades this crime went unsolved. Who killed Siobhan?Joining Nancy Grace Today:James Shelnutt - 27 years Atlanta Metro Major Case detective, SWAT Officer (RET) Attorney www.shelnuttlawfirm.com    Caryn Stark - NYC Psychologist, www.carynstark.com Chris Byers - former Police Chief Johns Creek Georgia, 25 years as Police Officer, now Private Investigator and Polygraph Examiner,   www.chrisbyersinvestigationsandpolygraph.com   Dr. Tim Gallagher - Medical Examiner State of FloridaShera LaPoint - Genetic Genealogist, The Gene Hunter,   www.thegenehunter.com   David Mittleman - CEO  Othram Incorporated, www.othram.com     Ray Caputo Lead News Anchor for Orlando's Morning News, 96.5 WDBO