"Contrary to Director Cheatle's public statement about the 'safety' of the sloped roof of American Glass Research Building 6, one whistleblower with direct knowledge of Secret Service planning for the event alleges that there was supposed to be a law enforcement presence on the roof that day," Hawley said in a letter to Homeland Security Secretary Alejandro Mayorkas on Monday.
The whistleblower alleges that at least one security officer was specifically assigned to be on the roof for the duration of the Trump rally, but this individual abandoned his or her post due to the hot weather, according to Hawley.
Hawley added that the whistleblower further alleges that concerns over the hot weather prompted law enforcement to neglect to patrol the building and instead to station security personnel inside the building.
The senator is asking Mayorkas to provide all records that may be related to this whistleblower's accusations by July 26.
On July 13, a gunman attempted to assassinate Trump during a campaign rally in Butler, Pennsylvania, shooting him in the right ear, killing one audience member and wounding two others.