A Denver hospital said Monday it has asked every patient who had surgery there over a six-month period to come in for a blood test amid allegations that a former technician exposed up to 6,000 people to hepatitis C as she fed her painkiller addiction.

Kristen Diane Parker, 26, is accused of injecting herself with painkillers meant for patients, then filling the used syringes with saline solution. She was arrested Friday and appeared in court Monday to be advised of the charges.

Thousands of patients at two hospitals where Parker worked were exposed, and nine have tested positive for hepatitis C, according to state medical officials and an investigator's affidavit. It was not known how many had yet to be tested.

U.S. attorney's office spokesman Jeff Dorschner said he could not comment on the case because the investigation is ongoing.

Parker started working at Rose Medical Center on Oct. 21. She was suspended April 13 after authorities began investigating her, and was fired April 22 after testing positive for the painkiller Fentanyl, the affidavit said.

Parker then went to work for the Audubon Ambulatory Surgery Center in Colorado Springs. She was there from May 4 until Monday.

Leslie Teegarden, a Rose Medical Center spokeswoman, said the hospital is being abundantly cautious and has notified every patient who had surgery while Parker worked there. Those patients are being asked to come in for a free blood test.

Amy Triandiflou, a spokeswoman for the Audubon hospital, said they hired Parker before she was fired from Rose. Triandiflou said state health officials informed the Audubon hospital of the investigation against Parker on July 1.

Rose Medical Center officials said Parker took a blood test before starting her job in October, and tested positive for hepatitis C. But Parker's attorney, Gregory Graf, said Parker did not find out she had the disease until police contacted her, which was sometime in April

"If Rose (hospital) is indicating that she knew, then the question is, 'Why did they allow her to continue work as a surgical scrub nurse?'" Graf said.

Teegarden said people with hepatitis C are not prohibited from working at a hospital.

Hepatitis C is a blood-borne disease that can cause serious liver problems, including cirrhosis or liver cancer. Symptoms include nausea, diarrhea, fatigue, pain and jaundice.

Parker, who remains in custody, will be in court again Thursday for a preliminary hearing on charges of tampering with a consumer product, creating a counterfeit controlled substance, and obtaining a controlled substance by deception or subterfuge. Bail is expected to be set at that hearing.

If convicted of all charges, Parker faces a maximum of 34 years in prison.