Secret Service under Homeland Security inspector general investigation after Trump assassination attempt

The Department of Homeland Security's inspector general has opened an investigation into the Secret Service's handling of security for former President Trump's rally in Pennsylvania over the weekend.

In a brief notice posted to the inspector general’s website, the agency said the objective of the probe is to "Evaluate the United States Secret Service’s (Secret Service) process for securing former President Trump’s July 13, 2024 campaign event," during which there was an assassination attempt against Trump.

There was no date given for when the investigation was launched. The notice was among a long list of ongoing cases that the inspector general’s office is pursuing. President Biden had already directed an independent review of the security at the rally.

Questions remain on Wednesday surrounding how the 20-year-old shooter, Thomas Matthew Crooks, managed to climb on top of a building and open fire at Trump and rally attendees in Butler, Pennsylvania.

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Secret Service Director Kimberly Cheatle said in an interview Tuesday that her agency was "solely responsible" for the implementation and execution of security there.

Cheatle told CNN that no assets from the rally were diverted on the day Trump was shot, even though other events in the state required Secret Service protection.

"At that particular site, we divided up areas of responsibility, but the Secret Service is totally responsible for the design and implementation and the execution of the site," Cheatle said. 

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Cheatle, in a separate interview with ABC News, said the agency was aware of the security vulnerabilities presented by the building Crooks took a sniper's position on aiming at Trump.

"That building in particular has a sloped roof at its highest point. And so, you know, there's a safety factor that would be considered there that we wouldn't want to put somebody up on a sloped roof. And so, you know, the decision was made to secure the building, from inside," she said.  

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But the "sloped roof" comment is facing scrutiny, with critics on social media calling it a "total BS excuse" that "defies believability." 

Fox News' Chris Pandolfo and the Associated Press contributed to this report.