The House Oversight Committee subpoenaed U.S. Secret Service director Kimberly Cheatle to testify about the "security lapses" that led to Saturday’s attempted assassination of former president Donald Trump.

"The assassination attempt of the former President and current Republican nominee for president represents a total failure of the agency’s core mission and demands Congressional oversight," Rep. James Comer (R., Ky.), chair of the House Oversight Committee, wrote in the subpoena.

The committee hearing hopes to clarify "how a rooftop within proximity to President Trump was left unsecure." The House Oversight Committee hearing, which is scheduled for Monday, is the first congressional investigation into the attempt on Trump’s life Saturday in Butler, Pa. 

During a campaign rally, the former president was shot on stage by 20-year-old Thomas Matthew Crooks, who was positioned about 400 feet from Trump’s podium on a rooftop with a direct line of sight to the candidate. Rally-goers saw Crooks, armed, on the roof before he took the shot and warned authorities of his presence. Three USSS snipers were in the building he was atop. After Trump was hit, his USSS detail jumped to cover him, and counter-snipers fatally shot Crooks.

Former U.S. Army sniper and Florida Rep. Cory Mills (R.) said the building Crooks shot from was an "obvious threat," calling the position a "sniper’s paradise."

"The amount of negligence, the amount of mistakes that was made here, I have a very difficult time not leaning myself towards this was intentional as opposed to fecklessness," Mills added.

Given the Secret Service’s failure to secure the venue perimeter, Comer also called into question Cheatle’s ability to lead the Secret Service.

Many Republican party leaders have called on Cheatle to step down since the former president’s life was almost taken, including House speaker Mike Johnson (R., La.) and House majority leader Steve Scalise (R., La.).

Cheatle acknowledged that "the Secret Service is responsible for the protection of the former president," adding, "the buck stops with me," during an interview with ABC News on Monday.

In 2014, Julia Pierson, the director of the Secret Service under then-president Barack Obama, resigned after a series of security lapses far less severe.

Comer wrote that he subpoenaed Cheatle due to her "lack of transparency and failure to cooperate."

"The lack of transparency and failure to cooperate with the Committee on this pressing matter by both DHS and the Secret Service further calls into question your ability to lead the Secret Service and necessitates the attached subpoena compelling your appearance before the Oversight Committee," Comer wrote.

The House Committee on Homeland Security will hold a hearing into the matter on Tuesday, and the House Judiciary Committee will hold an event on Wednesday to examine the FBI's investigation of the assassination attempt.