(NewsNation) — As the investigation continues into the assassination attempt on former President Donald Trump, a series of questions remain unanswered as federal law enforcement officials and lawmakers try to better understand the security breakdowns that occurred at the Pennsylvania rally this month.

U.S. Secret Service Director Kimberly Cheatle resigned under pressure this week and acknowledged that her agency failed in carrying out its plan to keep the former president safe. Trump has blamed President Joe Biden’s administration, claiming it failed to adequately protect him.

Before resigning, Cheatle told the House Oversight Committee that the Secret Service’s shortcomings fall squarely on her shoulders and what the agency should have done differently on July 13 is “never far from my thoughts.”

Yet as the FBI and others work to determine where security breakdowns occurred at the rally, public officials and others continue to push for more details into the incident and the motives of the suspected shooter, Thomas Matthew Crooks.

Where did the security break down?

While shouldering responsibility for the Secret Service’s failings, Cheatle sidestepped several key questions posed to her by the congressional committee.

Included in those inquiries were questions about whether the Secret Service had secured the building where Crooks was positioned at the time of the shooting.

“I’m not going to get into specifics of the day,” Cheatle told lawmakers this week. “There was a plan in place to provide overwatch, and we are still looking into responsibilities.”

Cheatle testified that the sloped roof of the building prevented the Secret Service from placing an agent at the site, which Paris said was assigned to the Beaver County Emergency Services Unit.

In an interview with ABC News, Cheatle said the sloped roof presented a “safety factor” issue, which led to the decision to have the building secured from the inside. She called the rally shooting “unacceptable.”

However, Pennsylvania State Police Commander Christopher Paris testified this week that the breakdown in security at the rally stemmed from a lack of communication between the Secret Service and state and local law enforcement agencies who were assisting with security measures at the rally,

Other officials claimed that communications between the Secret Service and other supporting agencies had been limited.

Paris testified how an initial planning meeting took place on July 8 before a final walk-thru took place three days later. He said that during the walk-thru, Beaver County, Pennsylvania law enforcement officers had identified the AGR Industries, Inc. building as a possible risk to which Secret Service officials said the building would be secured.

However, after Crooks was spotted – first by rally attendees and later by local officers – keeping tabs on him broke down before the shots were fired at Trump.

Paris said that Beaver County officers left their post to search for Crooks. A local officer was hoisted in an attempt to gain access to the roof when Paris said that Crooks pointed his assault rifle at the officer, who then dropped to the ground.

However, Butler County District Attorney Richard Goldinger told NewsNation that Paris’ assertion that the officers left their assigned area to find Crooks is untrue.

“He’s wrong about that,” Goldinger told NewsNation’s Brian Entin, adding, “Maybe that’s what he was told and that’s what he believed happened, but that’s not what happened. They did not leave — they just couldn’t see where he was from where they were.”

Goldinger told NewsNation that Butler County officers could not see where Crooks was when he was on the roof.

Paris testified that two or three minutes after the officer attempted to get onto the roof, several shots were fired by the gunman, one of which pierced through Trump’s ear. The shooting left one person dead and another wounded.

Is it the Secret Service’s fault or local law enforcement?

Because the event involved the former U.S. president, the Secret Service served as the lead agency handling security. The FBI’s Pittsburgh Field Office, along with the Pennsylvania State Police, Beaver County Sheriff’s Department, and other local agencies all provided support.

Paris testified state police troopers were assigned to a support role that included assistance with Trump’s motorcade and to two security posts within the secured perimeter. Officers from the Beaver County ESU were assigned to the building from where Crooks took the shots.

When questioned no federal agents were assigned to the sloped roof building where Crooks was positioned, Patrick Yoes — the national president of the Fraternal Order of Police — testified this week that security assignments came from Cheatle’s agency.

“I would say that again the primary responsibility of making these calls, making these decisions, and making the operation plans is going to be the Secret Service,” Yoes told lawmakers.

Bodycam footage that was released this week shows confusion among investigators immediately after the attempt on Trump’s life. The footage, posted by Sen. Chuck Grassley, shows officers attempting to figure out what had happened after Crooks was shot and killed by a sniper.

What was Thomas Matthew Crooks’ motive?

FBI Director Christopher Wray told lawmakers Wednesday that the agency is still working to determine what motive Crooks had in attempting to shoot and kill Trump.

“We’re hoping to learn more,” Wray said during a hearing on Wednesday. “It’s fair to say we do not yet have a clear picture of his motive.”

However, on the day Crooks registered for the Butler rally on July 6, he also ran a Google search on his computer asking how far Lee Harvey Oswald was from President John F. Kennedy when Kennedy was assassinated in Dallas in 1963.

That online search, Wray said, provides insight into Crooks’ mindset in the days leading up to the assassination attempt. Wray also testified the online searches began to focus more on Trump and the Butler rally.

Wray testified Crooks flew a drone about 200 yards from the stage where Trump was set to speak more than two hours before the shooting took place.

Crooks, a 20-year-old nursing home employee who graduated from community college last spring, had searched online for information about Trump and Biden and had photos of both men on his phone, lawmakers told the Washington Post.

The newspaper also reported that photos of U.S. Attorney General Merrick Garland and a member of the British royal family were also on Crooks’ phone. Wray testified that Crooks was using an encrypted messaging app on his phone.

A search of Crooks’ phone by the FBI also determined that he had conducted online searches about a shooting in which a teenage gunman, Ethan Crumbley, killed four high school students in Michigan as well as information about major depressive disorder, the rally in Butler, and the Democratic National Convention.

NBC News reported other online searches run by Crooks in the months leading up to the rally included one on explosive materials and chemical compounds as well as improvised explosive devices and the Department of Homeland Security.

The report indicated there were more than 14,000 links and photos found on Crooks’ phone, including one photo of the rally that was taken before Trump took the stage.

Did the shooter have other plans?

Wray testified that Crooks visited the Butler rally site the day after he registered and then returned three times the day of the event.

Crooks was seen by attendees carrying a range finder and a duffel bag 60 minutes before the shooting took place, CBS News reported.

In addition to the range finder and duffel bag, media reports said that Crooks had two cell phones, one of which was at his house. In addition, FBI agents also found three explosive devices, two of which were in his car, and the other was found at his home, NBC News reported.

After visiting the Butler rally site for about 70 minutes in the early morning hours of the day of the rally, Crooks returned to the site shortly after 5 p.m., which was just an hour before the shooting took place.

The CBS News report indicated Crooks’ father called police before the rally and expressed concern about his son and his whereabouts. The family is cooperating with the investigation.

However, in addition to not being able to provide a motive, investigators have not determined if Crooks had a bigger plan outside of targeting Trump at the Butler rally.

Why didn’t the Secret Service or law enforcement act sooner?

Wray testified the FBI is working to determine a timeline of events surrounding the attempt on Trump’s life.

Crooks was shot and killed by a sniper shortly after the shots were fired at Trump as Secret Service agents rushed to the stage to protect the former president and move him from the stage to a private vehicle.

However, why more attention wasn’t paid to Crooks’ presence on the roof of the building in the 26 minutes after a photo of Crooks situated on the nearby rooftop was sent to a local officer inside of the Secret Service Command Center remains unknown.

According to multiple media reports, attendees who spotted Crooks alerted police officers of Crooks’ presence. However, CBS News, citing law enforcement sources, said that attendees were unaware that Crooks had a gun in his possession.

Wray testified that Crooks used a gun with a collapsible stock, which made the weapon easier to conceal.

Because of Crooks’ ability to hide the weapon from sight, Wray said that attendees and officers who saw Crooks would not have seen the gun.

The local prosecutor said that local officers assigned to the AGR building would have had to lean out of the building where they were assigned to get a good look at Crooks, leaving him with time to get into position and get off the shots that were directed at Trump.

How could Secret Service protection measures change?

Since the shooting, the Secret Service has urged the Trump campaign to stop holding large outdoor rallies similar to the one in Butler.

NewsNation reported that future campaign events will be held indoors and other venues with more controlled entrances and that there will likely not be any outdoor events, regardless of size, held in the near future.

In an interview with NewsMax, Trump said that his campaign had been asking the Secret Service for more agents to “beef it up” at his rallies and were “consistently denied.”

A message sent to a Secret Service spokesperson about the agency’s security plans for future events involving U.S. presidents and presidential candidates was not immediately returned to NewsNation.

Meanwhile, Biden has directed the Secret Service to provide protection to independent presidential candidate Robert Kennedy, Jr. following the attempt on Trump’s life. Kennedy’s uncle, John F. Kennedy, and his father, Sen. Robert F, Kennedy, were both assassinated.

The Associated Press reported last October that a man was arrested for twice trespassing at Kennedy’s home in Los Angeles a month after an armed man who police said was impersonating a federal agent was arrested outside of a campaign event.