DENVER — Rocky Allen, the former surgical technologist at Swedish Medical Center who is accused of changing syringes and putting thousands of patients at risk for HIV, hepatitis B and hepatitis C, pleaded not guilty in a federal court on Friday.

He was released on a $25,000 unsecured bond, meaning he signed a document promising to pay the money if fails to appear in court. Department of Justice spokesman Jeffrey Dorschner said Allen was then sent to a halfway house where he will receive drug treatment.

Allen, who was arrested and charged earlier this week after being indicted by a federal grand jury, is charged with one count of tampering with a consumer product and one count obtaining a controlled substance by deceit. He could be sentenced up to 14 years in prison and fined up to $500,000 if convicted on both counts.

According to the indictment, Allen tried to remove a syringe containing fentanyl citrate and replace it with a similar syringe with another substance. Allen is also alleged to have knowingly and intentionally acquired fentanyl citrate, a controlled substance, by deception and subterfuge.

Because of that, Swedish Medical Center has asked about 3,000 patients who had surgery between Aug. 17 and Jan. 22 in the main operating rooms and in the orthopedic operating room on Oct. 28 to be tested for HIV, hepatitis B and hepatitis C.

Denver attorney James Avery said this week that two patients have tested positive for hepatitis.

Dorschner said as a result of Allen’s use of fentanyl, the surgical technician has been fired from Swedish Medical Center in Englewood, John C. Lincoln Medical Center in Phoenix, Banner Thunderbird Medical Center in Glendale, Arizona and Scripps Health in San Diego.  There is an investigation underway into Allen’s conduct at Northwest Hospital in Seattle.