MADISON, Wis. (AP) — A Wisconsin pharmacist accused of trying to spoil dozens of vials of COVID-19 vaccine has been charged with attempted misdemeanor property damage.

Online court records indicate Steven Brandenburg was charged Tuesday in Ozaukee County Circuit Court. He pleaded not guilty.

Prosecutors have warned more serious charges could follow if tests show the Moderna vaccine doses were ruined.

Investigators believe Brandenburg intentionally removed 57 vials from a refrigerator at Advocate Aurora Health in Grafton. Detectives say Brandenburg is an admitted conspiracy theorist who thought the vaccines would mutate recipients’ DNA.

The vials contained enough doses to inoculate more than 500 people.