Hundreds of painkillers intended for residents of a Duluth nursing home were stolen by a staff nurse earlier this year, leaving at least one patient in "extreme pain," state health investigators disclosed this week.

The nurse, who worked at Ecumen Lakeshore for four years, was suspended and quit soon after being confronted by her employer, according to the state Health Department report.

Ecumen officials notified authorities of the thefts in mid-May. A police spokesman said there was not enough evidence to pursue a criminal case against the nurse.

"The former employee's actions are a gross violation of everything we stand for at Ecumen and the nursing profession stands for," spokesman Eric Schubert said on Thursday. "We're sorry that this incident occurred, and we thank the patient who helped us uncover the thefts."

The case is the latest in a series of painkiller thefts that have alarmed state officials and led to the creation of a special task force of health care and law enforcement officials early this year. Their review found 250 cases of prescription drugs being stolen or reported missing at Minnesota health care facilities from 2005 to 2011.

The Duluth thefts, involving the powerful narcotic oxycodone and other drugs, came even though the nurse had been instructed on administering and tracking controlled substances, the Health Department said.

The thefts, totaling 764 pills meant for 34 residents, occurred over a five-month period. They ended shortly after a resident who didn't receive her oxycodone reported in late April that she was "having extreme pain" without the medication, the report said.

The report noted that the stolen painkillers were to be administered on an "as-needed" basis at the residents' request. No regularly scheduled pain medications were stolen, Schubert said.

The Health Department does not release the identities of the employees or residents in such investigations.

The number of reported drug thefts at Minnesota hospitals and nursing homes has more than doubled since 2005, according to the state task force.

The trend reflects what experts say is a nationwide surge of prescription-drug abuse -- in many cases by the very people entrusted with caring for patients.

Paul Walsh • 612-673-4482