A onetime Twin Cities pharmacist has pleaded guilty to stealing roughly 20,000 doses of addictive drugs over several years from his workplace.

Jeffrey F. Grothaus, 49, admitted to four counts of theft by swindle in Hennepin County District Court ahead of sentencing on Aug. 29.

The charges said Grothaus stole the pills from two Park Nicollet stores: Carlson Pharmacy on Twelve Oaks Center Drive in Minnetonka and Wayzata Pharmacy on North Central Avenue in Wayzata.

Grothaus, of Maple Grove, remains free ahead of sentencing. His attorney was not immediately available Tuesday to comment.

A Minnesota Board of Pharmacy investigation, which led to Grothaus having his license suspended indefinitely, found that he "admitted consuming the drugs while on duty."

"The opioid crisis has opened everyone's eyes to the abuse of prescription medications," County Attorney Mike Freeman said in a statement issued when Grothaus was charged in late March. "While Mr. Grothaus says he used the stolen pills for his own addiction, we cannot have these powerful drugs leaking out into the community, which is why we are prosecuting a pharmacist."

Grothaus is accused of stealing five types of drugs, mostly the sedative zolpidem (sold under the brand name Ambien) and the opioid painkiller tramadol (brand name Ultram).

The plea deal includes no agreed upon sentence. Each side will present its arguments for what they think Judge Tanya Bransford should hand down. Each felony count carries a maximum sentence of five years.

According to the criminal complaint:

An internal investigation by HealthPartners at the two Park Nicollet pharmacies in July 2016 found unusually large adjustments to the stores' inventory.

For example, an adjustment for 500 tablets of Zolpidem was entered into the computer at the Wayzata pharmacy. However, a search of all HealthPartners/Park Nicollet pharmacies failed to show those 500 pills turning up somewhere else.

The adjustment was made at a pharmacy technician's computer station. Store video showed Grothaus at that station. Video also showed Grothaus taking an item, slipping it into his pocket, then removing it from his pocket and putting it in his work locker.

Five months later, Grothaus admitted that he began stealing drugs in June or July of 2012.

Paul Walsh • 612-673-4482