ST. PAUL (AP) &045; A nurse who set up an unauthorized flu shot clinic at a Minneapolis college pleaded guilty Thursday, admitting she used diluted vaccine left over from an earlier clinic and kept cash paid by patients for herself.

Under the plea agreement, Michelle Torgerson, 33, of Albertville, faces up to one year in prison on a felony charge of dispensing a drug without a prescription. A sentencing date has not been set.

Torgerson had denied wrongdoing since her arrest last December, after officials at the Minneapolis school reported that several students and staff members had paid $20 to get shots.

She had been indicted last month on three counts of mail fraud, one count of adulteration of a drug and one count of dispensing drugs without a prescription. The U.S. Attorney’s Office agreed to drop the first four counts in exchange for pleading guilty to the last count.

In the plea agreement, Torgerson admitted she thinned flu vaccine with saline to increase the quantity of her supply. State health officials said the diluted vaccine wasn’t harmful, but wouldn’t have been effective against flu.

Torgerson also told U.S. District Judge Richard Kyle that she misrepresented that she was working for the American Heart Association. She said she kept the cash that customers paid for flu shots &045; about $580 &045; for herself. She turned the checks in to the American Heart Association for her daughter’s unrelated fundraising contest.

About 43 people at the college were given the shot, court documents said.

She got the vaccine from her employer, Maxim Healthcare Services, which ran flu shot clinics throughout the country.

Torgerson also will cease practicing, under an agreement with the Minnesota Board of Nursing. The Board could suspend or revoke her nursing license indefinitely.

Torgerson’s attorney did not immediately return a phone message left at his office after business hours Thursday.