CNN (07/28/12) Elizabeth Cohen

A spokesperson for the American Registry of Radiologic Technologists would not say Friday whether the group knew about a 2010 incident in which traveling technician David Kwiatkowski allegedly tested positive for illegal drugs and was fired from a Phoenix hospital. Following the termination, Kwiatkowski worked for four more hospitals in four other states. He allegedly has infected 30 people in New Hampshire with hepatitis C via used syringes. Exeter Hospital says it consulted the radiologic technologist registry prior to hiring Kwiatkowski and he held the required certification for the job.