There are now two working theories on how Thomas Crooks got a DPMS AR-15 rifle onto the roof of the AGR building in Butler, Pennsylvania last Saturday without being noticed prior to an assassination attempt on former President Donald Trump, who's now the 2024 Republican presidential nominee. 

According to a federal law enforcement source briefed on the investigation, Crooks either hid his father’s rifle near the AC unit he used to climb up onto the roof of the AGR building, or he had it in the backpack he was spotted with, along with the golf range finder.

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However, this source said hiding the rifle in his backpack would require a significant amount of disassembling and reassembling the rifle, and that the more likely scenario is that Crooks hid the rifle behind the AC unit.

Fox News has reported that Crooks bought a ladder and ammunition on the morning of the rally. However, federal law enforcement sources say that no ladder was found on site, and the working theory is that Crooks grabbed the rifle, climbed upon the AC unit and then climbed onto the roof.  

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We now also know that the unit inside that building was a Butler Township Emergency Services Unit sniper team who was doing "overwatch" on the event. This team was looking out of the windows of the building at the event, watching for any suspicious activity, while Crooks snuck up on the roof above them.

Fox News can also report that the Secret Service Counter Sniper who killed Crooks took only one shot.