What is the motive behind the Las Vegas massacre

With nearly 60 people dead and more than 500 injured after a mass shooting at the Route 91 Harvest Festival in Las Vegas on Sunday night, it became the deadliest shooting in modern American history. The gunman, Stephen Paddock, allegedly killed himself in his hotel room shortly before midnight and before police busted in. We look at what could have caused Paddock to commit the heinous crime.