William Osler Health System says an internal investigation has been launched after an employee allegedly accessed patient records to obtain narcotics.

In a statement issued Tuesday, William Osler Health System said that earlier this week, patients were notified about the data breach.

According to the statement, a staff member allegedly used patient health information to access Percocet for “non-hospital use.”

“The employee involved has not worked at the organization since the internal investigation was initiated, and Peel Regional Police and other appropriate authorities have been notified. Osler has fully cooperated with the police and other authorities, and will continue to do so,” the statement read.

“At Osler, our commitment to patients is paramount.”

William Osler Health System oversees operations at three Toronto-area hospitals, including Brampton Civic Hospital, Etobicoke General Hospital and Peel Memorial Centre for Integrated Health and Wellness.

The company has not yet said which of the three hospitals is impacted by the breach.

In a news release issued Wednesday, Peel police say the investigation into the case began in January 2017.

According to investigators, a 58-year-old woman was arrested in connection with the incident on March 30.

The woman, identified by police as Catharina Demme, who was employed as registered nurse at one of the hospitals, has been charged with breach of trust and theft under $5,000.

Meanwhile, William Osler Health System says it has put additional measures in place to make sure this type of data breach does not happen again.

“The hospital is also working to further strengthen policies and procedures related to this type of event, including regular proactive audits and reviews.”

Demme is scheduled to appear in court on May 4.

Anyone with information about the investigation is asked to contact police at 905-453–2121, ext. 2133.