Thomas Crooks left no manifesto or explanation for why he tried to kill the former and future president in Butler a year ago.
But a CBS News investigation is shedding light on his secret double life.
Before Thanksgiving 2023, Thomas Crooks' online life was fairly routine for a 20-year-old.
But the just-released investigation shows a plan for mass violence was brewing, and for it to succeed, Crooks had to compartmentalize his life.
CBS reports that in the summer of 2023, Crooks bought a rifle from his dad and signed up for a membership at a shooting range.
In the month before the July 13 shooting, Crooks researched the presidential candidates online more than 60 times.
He visited the Butler Farm Show grounds in person on July 7 and searched for Butler Farm Show photos.
The probe shows Crooks was planning an assassination, all while pursuing a career in engineering.
Ream more about the investigation HERE.