CONCORD, N.H. » A traveling hospital technician accused of infecting patients in multiple states with hepatitis C through tainted syringes pleaded guilty today in New Hampshire to 16 federal drug charges under an agreement that calls for him to serve 30 to 40 years in prison.

Judge Joseph Laplante asked David Kwiatkowski, 34, why he wasn’t going to trial. "Because I’m guilty," Kwiatkowski responded.

Kwiatkowski pleaded guilty to 14 charges of drug theft and tampering in New Hampshire, along with two similar counts in Kansas, although he was never formally charged there. Sentencing was set for Dec. 3, at which time the judge could impose a different sentence.

Before he was hired by New Hampshire’s Exeter Hospital in 2011, Kwiatkowski worked as a cardiac technologist in 18 hospitals in seven states, moving from job to job despite being fired at least four times over allegations of drug use and theft.

Forty-six people in four states have been diagnosed with the same strain of hepatitis C Kwiatkowski carries and is accused of spreading by replacing stolen painkiller syringes with saline-filled syringes tainted with his blood. Thirty-two patients were infected in New Hampshire, seven in Maryland, six in Kansas and one in Pennsylvania. Kwiatkowski also worked in Michigan, New York, Arizona and Georgia.

One of the Kansas patients died, and authorities say hepatitis C, a blood-borne virus that can cause liver disease and chronic health problems, played a contributing role. The charges Kwiatkowski admitted to in Kansas stem from the patient who died, and many of the other patients have experienced serious medical problems, U.S. Attorney John Kacavas said.

"Tragically, the defendant’s admissions of guilt today are too little, too late for those victims," he said. "There were many warning signs, there were many stop signs, there were many red lights along that road that were simply ignored by the defendant himself, a health care worker, by other individuals and entities in the health care industry."

Kwiatkowski grew up in Michigan and started his career there before becoming a traveling hospital technician who was assigned by staffing agencies to fill temporary openings around the country. According to the plea agreement filed Monday, Kwiatkowski told investigators he had been stealing drugs since 2002 — the year before he finished his medical training — and that his actions were "killing a lot of people." His lawyers have declined numerous interview requests.

Kwiatkowski told the judge today he was addicted to drugs and alcohol and was recently diagnosed with depression, for which he is taking several medications. Asked how he was feeling today, he answered, "good."

Kacavas said most of Kwiatkowski’s victims support the plea agreement, though some were disappointed that the proposed sentence wasn’t longer.

"I understand victims who want nothing less than a life sentence or the death penalty — I get that. But our system doesn’t allow for that," he said. "The victims support this disposition for the most part but are frustrated that they will carry this infection for the rest of their lives and feel that the defendant should spend the rest of his life beyond bars, which … if this 40-year sentence is imposed he may well do."

At least two dozen civil lawsuits related to his case are pending, most of them against Exeter Hospital, and while today’s plea rules out further criminal charges against Kwiatkowski, charges against hospitals or staffing agencies are possible, Kacavas said.

"Our investigation is not done," he said. "As we approach finality in his case, we are also looking elsewhere."