The chairman of the Senate’s Permanent Subcommittee on Investigations has issued a subpoena to the FBI seeking critical records related to last year’s assassination attempt against President Trump. 

One year later, “the American people still do not have answers to all of their questions about the breakdown of security at the Butler campaign rally and detailed information about the would-be assassin,” Senator Ron Johnson said in a statement Friday after the subpoena was served.

On June 13, 2024, during a campaign rally in Butler, Pennsylvania, gunman Thomas Matthew Crooks fired multiple rounds into the crowd from a rooftop near the rally stage. One bullet grazed Mr. Trump’s ear, while others struck attendees, killing firefighter Corey Comperatore and injuring several others. A sniper killed Crooks within less than a minute.

The senator’s subpoena demands access to security footage that may capture Crooks’ movements before the attack. It also seeks ballistics and bullet trajectory reports, drone analysis, and other critical records that could shed light on the tragic sequence of events. 

Mr. Johnson is also requesting access to Mr. Crooks’ social media and email accounts, internet search history, and call logs.

The Secret Service on Friday announced that it had suspended six personnel without pay, all of whom played some role in the miscues that made the assassination attempt possible. Secret Service deputy director Matt Quinn told CBS News that their penalties ranged from 10 to 42 days of leave, and that they were put on restricted duty or into roles with less operational responsibility upon their return. 

“Secret Service is totally accountable for Butler,” Mr. Quinn said. “Butler was an operational failure and we are focused today on ensuring that it never happens again.”

Mr. Johnson has expressed frustration with what he describes as the FBI’s and Department of Justice’s lack of transparency in the investigation. He accuses both agencies of withholding key information despite his repeated requests.

“I had expected the FBI to be more forthcoming with the public and provide my office with the records we have been seeking for months,” Mr. Johnson said. “I am issuing the subpoena to help prompt transparency and I look forward to [FBI Director Kash Patel’s] full cooperation.”

The senator has made gaining access to the records a priority, even in the face of resistance. “We’re continuing to be stonewalled, and I’m not happy about it,” Mr. Johnson told Fox News earlier this month, emphasizing the barriers his committee has encountered.

Mr. Johnson’s renewed push stems from the findings of a preliminary report produced by the Senate Homeland Security and Governmental Affairs Committee last year. The bipartisan investigation revealed significant lapses in the U.S. Secret Service’s preparation and response during the rally.

The report concluded that “failures in the U.S. Secret Service’s planning, communications, security, and allocation of resources for the July 13, 2024, Butler rally were foreseeable, preventable, and directly related to the events resulting in the assassination attempt that day.” Despite these findings, the report left many questions unresolved.

Mr. Johnson, who co-authored the preliminary report, intends for the final investigation to expose the full scope of the mistakes that were made. He also hopes for bipartisan support from his colleagues, although he is prepared to push forward independently if necessary.

“I’d like our report to be bipartisan, but everybody else seems to have been moving on here and not particularly interested in an investigation. I am,” Mr. Johnson said. “Whether I have the other officers involved or not, I’m moving forward, which is why I approved a subpoena.”