Thomas Matthew Crooks was casually strolling around the Butler, PA rally just hours before he attempted to assassinate Donald Trump ... new video shows.
Newly uncovered footage recorded at 4:26 PM shows Crooks in his final hours back on July 13 ... walking around the premises without his backpack -- or the rifle he later used in his failed assassination attempt on Trump.
In the footage, he’s seen gazing off into the distance in what was the calm before the storm.
The chilling clip's been making the rounds online ... captured and shared by a small business owner who was selling themed hats before the rally. He only realized he had captured Crooks on video after going back through his footage recently.
As we know, Crooks opened fire around 6:00 PM ... grazing Trump's ear and leaving bystander Corey Comperatore dead -- and loads of footage of Crooks up on the roof has been released since.
Earlier this month, video was released showing an officer being hoisted onto the roof where Crooks stationed himself. The officer bolted down after a confrontation with Crooks, racing to grab a bigger gun and calling for backup -- right when Crooks started shooting.
In the end, the cop made it to the roof and found Crooks dead and bleeding next to the gun used to fire at Trump.