A 27-year-old nurse from Grande Prairie has been charged with drugging some of her colleagues in a case that baffled police for two years.

Sarah Christine Bowes was charged Wednesday with more than 50 counts of mischief endangering life, administering a noxious substance and credit card fraud.

Dan MacLennan, president of the Alberta Union of Provincial Employees, says staff members at Queen Elizabeth II Hospital are relieved charges have been laid. He said the incident was traumatic for many employees.

"People got extremely sick and their families were really concerned. Worse than that [was] not knowing who it was that was the problem, or if it's a group of people or if it's a prank or a deliberate act," he said.

In early 2004, nurses began reporting flu-like symptoms, memory loss and spending more time than usual sleeping.

They said the illnesses continued for 17 months before suddenly stopping.

The hospital closed the floor and conducted air-quality and environmental tests, but lab results found nothing unusual.

Around the same time, staff reported stolen personal belongings and credit cards. They also told hospital authorities that they couldn't find some of the hospital's prescription drugs.

The RCMP now believe food and drinks of staff were spiked with drugs.

Police allege Bowes gave a prescription sedative in the benzodiazepine family of drugs to at least seven co-workers.

RCMP Cpl. Brent Mundle says patients were not drugged.

Bowes is scheduled to appear in court in Grande Prairie on Monday.