A pharmacist accused of deliberately spoiling more than 500 doses of coronavirus vaccine at a hospital outside Milwaukee was arrested Thursday afternoon, local authorities said.

Police in Grafton, Wis., arrested the unnamed man on recommended charges of first-degree recklessly endangering safety, adulterating a prescription drug and criminal damage to property. He is being held in the county jail, according to a statement from the police department.

The alleged tampering will delay inoculation for hundreds of people, health officials said, in a state where 3,8 new cases were reported and 42 people died Thursday of covid-19, the disease caused by the novel coronavirus, according to a state dashboard.

The pharmacist was dismissed earlier this week by the health-care system, Aurora Health Care. And authorities said he admitted in writing that he had removed 57 vaccine vials “knowing that if not properly stored the vaccine would be ineffective.” Police said they were withholding the man’s name until he was formally advised of the charges pending against him.