(CNN) -- A spokesman for a national registry of radiologic technologists declined Friday to say whether the group was aware of a 2010 incident in which David Kwiatkowski allegedly tested positive for illegal drugs and was fired from an Arizona hospital.
After being fired from the Phoenix hospital, Kwiatkowski went on to work at four more hospitals in four other states.
He was arrested this month in New Hampshire in connection with stealing drugs from a hospital, and it's believed he infected 30 people in that state with hepatitis C through infected syringes.
Exeter Hospital in New Hampshire said it consulted the American Registry of Radiologic Technologists before hiring Kwiatkowski and he held the required certification for his cardiovascular tech position.
The registry's website says Kwiatkowski's certification was "summarily suspended" as of July 2012.
Kwiatkowski was working at Arizona Heart Hospital in 2010 when a fellow employee found him passed out in the men's bathroom, according to documents obtained by CNN.
"I looked in the toilet and spotted a 5 cc syringe and a needle floating in the water," the employee said in a statement submitted to the Arizona Radiation Regulatory Agency. "The label was a blue fentanyl label... He then said 'Shit ... I am going to jail.'"
Fentanyl is a powerful narcotic frequently used in hospitals. Kwiatkowski flushed the syringe and needle down the toilet, according to the employee.
Kwiatkowski was immediately fired from Arizona Heart Hospital, according to a hospital spokeswoman. He then relinquished his license as a radiologic technologist.
"I don't have the resources nor money to fight the accusations," Kwiatkowski wrote at the time.
A few weeks later, he was working at Temple University Hospital in Pennsylvania, and then went on to work in Kansas and Georgia before working in New Hampshire.
The agency that placed Kwiatkowski in the Arizona job reported the incident to the American Registry of Radiologic Technologists, according to a spokeswoman for the agency, Springboard, Inc.
A spokesman for the national registry said they're investigating the allegations against Kwiatkowski. "Because we have strict confidentiality policies, the status of an ongoing investigation is not released," the registry said in a statement.
Christopher Cook, a spokesman for the registry, declined to comment further.
The director of the Arizona Radiation Regulatory Agency said officials stopped their investigation when Kwiatkowski moved out of state.
"We had no jurisdiction," said Aubrey Godwin. "If drugs or alcohol were involved, we would want to get blood tests done, but he was out of state, so it was sort of hard to implement."
An expert in so-called "drug diversion" said it's not uncommon for healthcare professionals to leave a state when they're being investigated for drug use.
"They just move on to the next job," said John Burke, president of the National Association of Drug Diversion Investigators. "This is a much bigger problem than most people realize."
Godwin, the director of the Arizona licensing board, said he's not sure if his group reported the 2010 incident to the national registry.
"It's not clear. I can't say. It would have been just a phone call, and I don't remember a phone call, but I'm not sure on that one," he told CNN.
In the Exeter case, Kwiatkowski has been charged with obtaining controlled substances by fraud and tampering with a consumer product, namely a hospital syringe, according to an affidavit filed in federal court. He is suspected of stealing fentanyl, the affidavit said.
Hepatitis C is considered to be among the most serious of hepatitis viruses. It is typically asymptomatic, going undetected until liver damage shows up, according to the Mayo Clinic.
New Hampshire's health department is asking everyone who was a patient in Exeter's operating rooms and the intensive care unit between April 1, 2011, and May 25 of this year be tested.
Those are two areas that Kwiatkowski visited during his "routine duties to transport patients," an Exeter Hospital statement said. But it added he "was not involved with procedures or patient care."
Exeter, in a statement, said it conducted a background check and took other steps before hiring Kwiatkowski full time.
U.S. Attorney John P. Kacavas said his office interviewed employees at Exeter who said they had seen Kwiatkowski acting strangely, one time sweating profusely and with bloodshot eyes.
"One of them described him as unfit to provide medical care and his supervisor sent him home," Kacavas said. "He provided a plausible explanation for his condition, which was that he had been crying his eyes out because his aunt had died and he was an emotional wreck."
According to state, county and hospital officials, he worked as a radiology technician and medical technician in cardiac catheterization labs in the following locations:
-- Oakwood Annapolis Hospital in Wayne, Michigan, January to September 2007;
-- Saint Francis Hospital, Poughkeepsie, New York, November 2007 to February 2008;
-- UPMC Presbyterian, Pittsburgh, March 2008 to May 2008;
-- Baltimore Veterans Affairs Medical Center, May 2008 to November 2008;
-- Southern Maryland Hospital, Clinton, Maryland, December 2008 to February 2009;
-- Maryvale Hospital, Phoenix, March to June 2009;
-- Johns Hopkins Hospital, Baltimore, July 2009 to January 2010;
-- Maryland General Hospital, Baltimore, January 2010 to March 2010;
-- Arizona Heart Hospital, Phoenix, March 2010 to April 2010;
-- Temple University Hospital, Philadelphia, April 2010;
-- Hays Medical Center, Hays, Kansas, May 2010 to September 2010;
-- Houston Medical Center, Warner Robins, Georgia, October 2010 to March 2011.
-- Exeter Hospital, Exeter, New Hampshire, April 2011 to July 2012.
Institutions say they are calling former patients and offering free testing, and that the U.S. Centers for Disease Control and Prevention is helping state health officers and hospitals tackle the problem.
Kwiatkowski was arrested earlier this month after police found him in a Massachusetts hotel room "in an intoxicated state" and took him to a hospital, the affidavit states. He is now being held in the Strafford County, New Hampshire, jail. He could face more than 20 years in prison if convicted.
Kwiatkowski appeared in New Hampshire federal court Tuesday and waived his right to a detention hearing. Kacavas said it is possible more charges could be filed.
Bjorn Lange, a public defender representing Kwiatkowski, told CNN Friday he would have no comment.
CNN's Jennifer Bixler, John Bonifield, William Hudson and Joe Sterling contributed to this report.