New Hampshire’s Exeter County Hospital is the center of a hepatitis C outbreak being felt nationwide and now under investigation by the FBI and U.S. Food and Drug Administration officials. The first diagnoses took place on May 31, and 20 patients have been diagnosed so far with a single strain of the hepatitis C virus (HCV).

Close to a thousand patients who used the hospital’s cardiac catheterization lab since October 1, 2010 have been asked to come in for screening. However, this is difficult for those who are no longer in the area—whether they’ve moved across country or, like one unidentified patient currently living in Florida, were only visiting the state when they were brought to the lab. An Exeter County Hospital spokesperson said the hospital would assist out-of-state patients in shipping blood samples to New Hampshire for testing.

“I am hysterical, scared and sleepless,” said the Florida patient, who is consulting her doctor to see how best to send blood samples to New Hampshire for testing; so far, two dozen blood samples collected in this way did not provide useful results because they weren’t tested quickly enough and became spoiled.

State health officials attribute the outbreak to “drug diversion” by an employee in the hospital’s cardiac catheterization lab. This is when a hospital worker injects him- or herself with drugs intended for patients, then refills the syringes with water or saline solution to hide the theft. The patients are then injected with the useless syringes, meaning they don’t get their drugs—and, as in cases like this one, are exposed to infection.

Federal and state officials are working to determine whether the outbreak is a criminal or civil matter. In a similar case in Colorado, a woman who spread hep C through drug diversion was recently sentenced to 30 years in prison.