A former surgery technician may have exposed thousands of Colorado patients to Hepatitis C when she swapped her own dirty syringes for ones filled with a powerful pain killer.

Kristen Diane Parker faces federal criminal charges for allegedly making the swaps while working at Audubon Ambulatory Surgery Center in Colorado Springs and Rose Medical Center in Denver.

Authorities say Parker admitted to changing out syringes with a saline solution with ones filled with the pain killer Fentanyl. Parker injected herself with the drug, according to the arrest papers, at work and at home.

The medical director at Audubon, Dr. Mike Hall, says he's worried. On Monday, they're sending out certified letters to 1,200 patients, telling them they need to get tested if they had surgery at the medical center from May 4, 2009 until July 1, 2009. That's the time period Parker worked at the surgery center. The Hep C testing is free. The center has also set up a hotline, where patients can call and speak to a representative about their concerns and testing. That number is now working. Call 1-719-571-4440 if you have questions or concerns.

An affidavit says at least nine surgery patients at Rose have tested positive for the Hepatitis C, which is incurable. About 5,000 patients are being advised they may have been exposed and need to be tested in Denver.

According to the arrest papers, Kristin Parker reportedly told investigators that she probably contacted Hep C when she using heroine last summer.

Dr. Hall says they aren't testing patients for any other diseases. Parker apparently has tested negative for Hepatitis B and HIV.

Rose Medical Center posted the following message on their Web site regarding the situation:
The Colorado Department of Health has contacted Rose Medical Center about a group of nine patients with hepatitis C who were treated at the hospital. All of these cases are under investigation by the Colorado Department of Health. The investigation is examining the possibility that a former Rose surgical room employee, who was terminated before the hospital learned of these cases, may be the source of the virus. That has not been confirmed. Right now, Rose is working closely with the Colorado Department of Health to determine all of the facts.

We consulted with the State Health Department and the Centers for Disease Control and decided the best precaution for our patients is to offer free, confidential and individual testing to everyone who had surgery at Rose Medical Center or at the outpatient surgery department in the Wolf Building at Rose between October 21, 2008 and April 13, 2009. Only patients who had surgery in the main hospital or the Wolf Building between October 21, 2008 and April 13, 2009 require testing.