PORT WASHINGTON, Wis. —

A fired Wisconsin pharmacist who is accused of intentionally spoiling more than 500 doses of the COVID-19 vaccine made his first appearance in court.

Steven Brandenburg, 46, of Grafton, was arrested Thursday.

He was being held in the Ozaukee County Jail.

Brandenburg appeared virtually for a probable cause hearing.

A certified letter listed recklessly endangering safety and criminal damage to property as possible charges.

A criminal complaint has not yet been filed.

Ozaukee County District Attorney Adam Gerol told a judge it remains unclear if the vials Brandenburg allegedly removed were destroyed or damaged by Aurora Grafton Medical Center.

That could dramatically impact the charges from felony to misdemeanor.

Gerol said he needs clarification from Aurora and the vials may also need to be tested by Moderna.

He mentioned during the hearing that Brandenburg brought guns to work on at least two occasions and hospital officials had concerns about him.

The judge set a $10,000 signature bond.

According to the probable cause statement, Brandenburg told investigators he removed the 57 COVID-19 vaccine vials from the freezer because he believed it was not safe and it could harm patients and change their DNA.

"He'd formed this belief they were unsafe," Gerol said.

The FBI and U.S. Food and Drug Administration are also investigating.

Advocate Aurora Health Care Chief Medical Group Officer Jeff Bahr said Brandenburg admitted to deliberately removing the vials from refrigeration on Dec. 24 into Dec. 25, returned them, then left them out again on the night of Dec. 25 into Dec. 26.

A pharmacy technician discovered the vials outside the refrigerator on Dec. 26.

Bahr said Brandenburg initially said he had removed the vials to access other items in the refrigerator and had inadvertently failed to put them back.

He was fired after admitting to intentionally damaging the vaccines.

The Moderna vaccine is viable for 12 hours outside refrigeration, so workers used the vaccine to inoculate 57 people before discarding the rest.

Police said the discarded doses were worth between $8,000 and $11,000.

Bahr said the doses people received Dec. 26 are all but useless.

MADISON, Wis. — A former Wisconsin pharmacist has pleaded guilty in federal court to charges that he tried to spoil dozens of vials of COVID-19 vaccine.

Prosecutors in January charged 46-year-old Steven Brandenburg, of Grafton, with two counts of attempting to tamper with consumer products.

Brandenburg pleaded guilty to both counts in a video conference with U.S. District Judge Brett Ludwig in Milwaukee on Tuesday. He could face up to 20 years in prison and $500,000 in fines when he's sentenced in June.

Police arrested Brandenburg on Dec. 31 as part of an investigation into how 57 vials of Moderna vaccine were left for hours outside a refrigerator.

According to court filings, Brandenburg believed the Moderna vaccine wasn't safe. There is no scientific evidence to support that contention.