Investigation into the shooter at Trump rally

The transcript covers the assassination of former President Donald Trump, focusing on the shooter, Thomas Crooks, a 20-year-old with a seemingly normal background. The FBI is investigating the incident, finding no clear motive and confirming Crooks acted alone. Congress is also probing the security measures at the rally. The community is shocked, as Crooks was known to be isolated and bullied, but not seen as a threat.

What was the nature of the investigation into the security measures at the rally?

What were the findings regarding the motive behind the shooting?