The suspect in the shooting targeting the Centers for Disease Control and Prevention had letters that showed his “discontent” with COVID-19 vaccines.

Investigators released a photo on Tuesday of the gunman, Patrick White, of Kennesaw. Channel 2 Cobb County Bureau Chief Michele Newell has been digging into White’s past, where she learned his father had called police about White’s mental health. GBI director Chris Hosey said White took his father’s guns for the attack.

Documents found in a search of the suspect’s home “expressed the shooter’s discontent with the COVID-19 vaccinations,” Georgia Bureau of Investigation Director Chris Hosey said.