But he’d also secretly amassed a massive arsenal of 42 firearms. At least one of those was automatic, while another two had been modified with legal bump-stock devices that allows semi-automatic guns to give full-auto fire of up to 800 rounds a minute. Several had scopes, and packed military-grade ammunition.

He took 23 of those guns into his Mandalay Bay suite over several days and set up two rifles on tripods at windows overlooking the Route 91 Harvest country music festival.

Thousands of rounds of ammunition were also found in the suite, enabling him to fire repeatedly over the course of 72 minutes. His car had several pounds of a fertilizer used in bomb-making.