Iannarelli added the gunman used “expensive guns and ammunition.”
Iannarelli noted that FBI and police are going to speak with every friend and relative, and are conducting forensic review of the suspect’s computers and phones.
The shooting at the sold-out Route 91 Harvest festival was the worst mass shooting in modern U.S. history. Forty-nine people were killed when a gunman opened fire at the Pulse nightclub in Orlando in June 2016.
Sunday’s shooting came more than four months after a suicide bombing at an Ariana Grande concert in Manchester, England, that killed 22 people. Almost 90 people were killed by gunmen inspired by Islamic State terror group at the Bataclan concert hall in Paris during a performance by Eagles of Death Metal in November 2015.