The man accused of killing a police officer while shooting at the U.S. Centers for Disease Control and Prevention (CDC) headquarters in Atlanta had previously been reported to police for suicidal thoughts and launched the deadly attack with his father’s weapons to send a message against COVID-19 vaccines,

The gunman who opened fire Friday at the US Centers for Disease Control and Prevention broke into his father’s safe to get the five firearms recovered at the scene, state investigators said Tuesday, as some CDC workers seeking answers and reassurance from leadership were left dissatisfied by a short agency-wide meeting about the shooting.

Documents found in a search of the home where Patrick Joseph White lived with his parents “expressed the shooter’s discontent with the COVID-19 vaccinations,” authorities said.