CONCORD - David Kwiatkowski, a former Exeter Hospital employee accused of spreading a hepatitis C infection to more than 30 patients was indicted Wednesday by a grand jury on 14 federal charges, U.S. Attorney John Kacavas said Wednesday night.

Kwiatkowski was indicted on seven counts each of tampering with a consumer product and diversion of a controlled substance, Kacavas said.

The 33-year-old Kwiatkowski remains behind bars after he was charged in connection with the hepatitis outbreak that infected 32 former patients. Hepatitis C is a potentially deadly virus that causes damage to the liver.

Federal authorities say Kwiatkowski swiped syringes containing the pain killer fentanyl, injected himself, and then returned the contaminated needles to be used on patients.

In July, he was charged with one count each of obtaining controlled substances by fraud and tampering with a consumer product.

"He was charged by complaint before. Now this has gone to a grand jury," Kacavas said.

He said the grand jury indictment reflects charges involving seven victims.

The indictment alleges that Kwiatkowski, knowing he was infected with the virus since at least June of 2010, “devised a scheme to obtain fentanyl for his personal use and abuse,” according to a press release from the U.S. Attorney.

Kwiatkowski is charged with “surreptitiously” taking syringes filled with fentanyl, a painkilller, that had been prepared for patients undergoing medical procedures, and replacing them with syringes he had previously stolen.

“Kwiatkowski used the stolen syringes to inject himself, causing them to become tainted with his infected blood, before filling them with saline and then replacing them for use in the medical procedure,” the press release states.

“Consequently, instead of receiving the prescribed dose of fentanyl, patients instead received saline tainted by Kwiatkowski's infected blood.”

According to the indictment, Kwiatkowski was employed for several years as a health care worker in Michigan. Beginning in 2007, he became a “traveling” medical technician, employed in New York, Pennsylvania, Maryland, Arizona, Kansas and Georgia.

He began working at Exeter Hospital in April of 2011 and was employed there until May of this year, when the first cases of hepatitis C were diagnosed in patients who had been treated at the hospital's cardiac catheterization lab.

Thousands of patients who underwent procedures or surgery at the hospital were tested for the virus, and 32 were diagnosed with the same strain of hepatitis C as Kwiatkowski, according to the state health department.Kwiatkowski was arrested July 19, and has been in custody ever since.

If convicted, he faces up to 10 years in prison on each count of tampering with a consumer product and up to four years in prison for each count of obtaining controlled substances by fraud. Each offense also is punishable by a fine of $250,000.

Numerous federal, state and local agencies have been investigating the hepatitis C outbreak, including the FBI, Drug Enforcement Administration, Office of Criminal Investigations of the Food and Drug Administration, New Hampshire Attorney General's Office, New Hampshire State Police and Exeter police.

Shawne Wickham of the New Hampshire Sunday News contributed to this story.