What did the FBI publicly conclude about the Butler, Pennsylvania shooting investigation?

1. The official characterization: assassination attempt and potential domestic terrorism

From its earliest public briefings the FBI described the incident as an assassination attempt on a former president and said it was being investigated as potential domestic terrorism, making the agency the lead federal law enforcement authority on the case and encouraging the public to submit tips and media ^[2][1][5].

2. Identification of the subject and the “acted alone” finding

The FBI publicly identified Thomas Matthew Crooks, 20, as the subject involved in the Butler shooting and repeatedly stated that, while the investigation to date indicated he acted alone, agents continued “logical investigative activity” to determine if there were any co‑conspirators ^[2][1].

3. What the FBI said about motive — publicly unresolved

The bureau stated explicitly that it had not identified a motive for Crooks’s actions and that determining motive was a central line of inquiry for the investigation, even as investigators pieced together timelines and search histories to try to understand the subject’s intent ^[1][3][6].

4. The forensic and investigative trail the FBI disclosed

Public briefings recounted detailed investigative findings: searches on the subject’s devices for campaign events and public figures, multiple queries about explosive devices dating back to 2019, the discovery of improvised explosive devices in the subject’s vehicle and a device in his bedroom, and other physical evidence such as a ladder left near his home rather than at the rally site — all presented as part of a comprehensive fact‑gathering effort ^[3][6][4][7].

5. Scope of FBI activity and public messaging about safety and openness to leads

The FBI repeatedly emphasized the scale of the probe, its coordination with the Secret Service and state and local partners, and that there were no current public safety concerns; the agency also left the door open to reopening or expanding the investigation should “credible new information” emerge, and consistently invited public tips and media submissions ^[1][2][5].

6. How the FBI’s public conclusions fit within wider scrutiny and alternative narratives

Congressional and local task forces later highlighted operational and security failures by law enforcement at the rally site — findings that focused on Secret Service and multi‑agency coordination rather than altering the FBI’s central public conclusion about the shooter’s status as the identified subject of the attack ^[8][9]. Separately, conspiracy claims and social‑media theories circulated, but the FBI’s public record emphasized evidence collection and stated conclusions rather than engaging with speculative narratives ^[10].

7. Closure and later public statement on lone‑actor finding (public record limits)

Subsequent reporting and secondary summaries indicate the FBI formally concluded its investigation in November 2025, publicly stating that Thomas Matthew Crooks planned and carried out the attack by himself and that investigators left no conclusive public explanation for motive — and that the bureau would reopen the matter only if credible new information surfaced ^[11][12]. This later closure is reflected in media summaries and encyclopedic entries that draw on the FBI’s public updates.

The FBI’s public posture across its briefings was methodical: identify the subject, treat the event as an assassination attempt and potential domestic terrorism, collect extensive digital and physical evidence, state that the investigation to date indicated a lone actor while continuing to seek co‑conspirators and motive, and invite public assistance — a narrative that stood alongside external inquiries that probed security failures and public skepticism propagated online ^{[2][1][3][8][10]}.