MADISON, Wis. (NewsNation Now) — Authorities arrested a suburban Milwaukee pharmacist Thursday suspected of deliberately ruining hundreds of doses of coronavirus vaccine by removing it from refrigeration for two nights.

The Grafton Police Department said the former Advocate Aurora Health pharmacist was arrested on recommended charges of reckless endangerment, adulterating a prescription drug and criminal damage to property. The department said in a news release that he was in jail. Police did not identify the pharmacist, saying he has not yet been formally charged.

Advocate Aurora Health Care Chief Medical Group Officer Jeff Bahr told reporters during a teleconference Thursday afternoon that the pharmacist deliberately removed 57 vials of the Moderna vaccine from refrigeration overnight on Dec. 24 into Dec. 25, returned them, then left them out again on the night of Dec. 25 into Saturday.

A pharmacy technician discovered the vials outside the refrigerator on Saturday morning. Workers used the vaccine to inoculate 57 people. Bahr said their doses were ineffective. He stressed that the facility’s security protocols are sound.

“This was a situation involving a bad actor, as opposed to a bad process,” he said.

The Moderna vaccine is viable for 12 hours after being removed from refrigeration. In light of that, Bahr said medical personnel used doses from the thawed vials to inoculate 57 people on Saturday and discarded the rest.

He said officials in the health system suspended the pharmacist after growing more suspicious over the next few days. After multiple interviews, the pharmacist admitted Wednesday to deliberately removing the vials from the refrigerator

The Grafton facility hadn’t received any Moderna vaccine before Dec. 24, which means the pharmacist wouldn’t have had an opportunity to tamper with any other vials, he added.

“We continue to believe that vaccination is our way out of the pandemic. We are more than disappointed that this individual’s actions will result in a delay of more than 500 people receiving their vaccine,” the health care system said in a statement.

The number of COVID-19 cases in Wisconsin has been rising in recent days after dipping in early December. The state reported 3,170 newly confirmed cases on Thursday, according to data compiled by Johns Hopkins University. The state has now seen 516,226 cases.

The Associated Press contributed to this report.