A medical technician was charged with spreading hepatitis C to 30 New Hampshire hospital heart patients by allegedly reusing syringes he stole to inject himself with a potent narcotic, the U.S. attorney announced this afternoon.

Federal investigators are checking for hepatitis C cases at hospitals in at least six other states where the technician worked when he was a so-called traveler. The states were not identified.

David Matthew Kwiatkowski, 33, was charged with obtaining controlled substances by fraud and tampering with a consumer product, U.S. Attorney John Kacavas said at a news conference in Concord, the Fosters's Daily Democrat reports. He was arrested today at a Massachusetts hospital where he was receiving undisclosed medical treatment and will be extradited to New Hampshire when he is released, the Union Leader says.

Kwiatkowski, a Michigan native, began working in Exeter Hospital's cardiac catheterization laboratory in April 2011 when he was a traveling technician. He became a full-time employee last October and was fired after the liver-damaging, viral infections were detected in late May.

BLOG: N.H. hospital shuts lab after 4 patients get hepatitis C

Kacavas said investigators uncovered evidence that Kwiatkowski has carried the disease since at least June 2010, although Kwiatkowski claimed he learned only in May that he was infected.

Kacavas alleged that Kwiatkowski stole syringes, injected himself with fentanyl, then refilled the syringes with a different liquid to conceal the theft. The syringes were then used on patients.

Kwiatkowski should not have had access to fentanyl. Kacavas would not say how investigators believe he got the powerful synthetic anesthesia drug.

In addition to 30 heart-catheterization patients, one hospital employee has tested positive for the disease, which inflames the liver and can lead to cirrhosis, cancer, transplant or death.

The Exeter News-Letter has more about the case.

The outbreak has resulted in two dozen lawsuits, including a possible class-action suit that involves 90 people, a lawyer tells the Portsmouth Herald. He said 1,100 people may potentially be affected.

Four years ago, Nevada experienced one of the nation's largest hep C outbreaks after another anesthesia drug was misused at two Desert Shadow Endoscopy Center clinics, infecting 114 patients.

Some of the infected patients spoke about their slow recovery. The operator, Dipak Desai, has been indicted and is awaiting trial.

Multiple lawsuits were settled, and a drug company paid out $552 million.

Update at 5:26 p.m. ET: In a statement, Exeter Hospital says "pre-employment drug testing and standard and criminal background checks were performed" on Kwiatkowski before he was hired full time, which is the practice with all "travelers" -- medical technicians who move around the country on temporary assignments.

The statement says that because "this remains an ongoing criminal investigation, we are unable to comment on any of the details related to the case" and that besides being a former employee, Kwiatkowski was a patient, "which further limits our ability to comment more specifically."

After the outbreak was discovered, the hospital created a hepatitis C information and resources page.