Shocking new theory behind Vegas shooter killing spree

Months after gunfire rained down on thousands of Las Vegas concert goers, killing 58 people and wounding more than 800 others, many questions remain. Nancy Grace visits the scene in a search for answers. Did Stephen Paddock act alone? What was his motive for the massacre? Grace's guests in this episode including lawyer and shooting survivor Brian Claypool, medical examiner Dr. William Morrone, forensic psychiatrist Dr. Carole Lieberman, and reporter John Lemley.