Investigators revealed that Thomas Crooks purchased 50 rounds of ammunition the day of the rally in Butler, Pennsylvania.
Though they've talked to hundreds of people and scoured Crooks' phone and social media, investigators have not been able to pinpoint his motive.
Trump's attempted assassination and the bystander's death that followed came during a time of deep political division. The images of Sunday's shooting have been a source of stress for many.
Action News' Alicia Vitarelli spoke with a psychologist on Tuesday about the mental health impact of this incident.
Watch the video above to learn more.