Ronald Hough, 45, of Tega Cay is accused of using fake names and phony Social Security numbers to get painkillers from Piedmont Medical Center in Rock Hill.
The hospital said Hough had used at least five aliases since 2006 when visiting the emergency room there.
On Friday, he was arrested in the parking lot of the hospital after a nurse recognized him from a past visit when he had used a different name.
"The criminals have the advantage here," said ER nursing director Teresa O'Neill. "It's easy to change how you look. Change the color of your hair, or grow a beard."
The hospital saw 67,000 patients in the emergency room last year, and employees are required to treat everyone who walks in the door. Spotting fraud often requires very close observation, or an employee remembering a particular incident.
"Unless they do something unusual during their visit, there's nothing in that nurse's or physician's or PA's mind to remember that patient."
O'Neill said people seeking drugs often go to extreme lengths to get them. They show up at different times of the day so the same nurses and doctors are not working.
"We have patients who monitor the cars in the parking lot, too. They know which doctors drive which cars," O'Neill said. "They're savvy at this."
The hospital is looking into ways to monitor people who come into the ER more closely. However, technology such as photo IDs, fingerprinting or handprint scans are expensive, and they would have to use it for every patient who walked in. Right now, it's just not feasible.
Plus, PMC officials said they can't be detectives. They must focus on patient care, and that often means taking a patient at their word.
"We would never deny care to anyone. We can't require proof of who they are. We have to take it that they're telling the truth," O'Neill said.
Hough is out of jail on a $9,000 bond. He's charged with obtaining drugs by fraud, habitual offender and driving under suspension third offense.
Channel 9 made another discovery about Hough while checking his criminal record on Monday afternoon.
He has a reckless homicide charge from 1995. Prosecutors said Hough drove the wrong way on I-77 and hit a person head-on. That person later died.
Prosecutors said the case was never prosecuted for several reasons. Hough disappeared for several years, and a bench warrant was issued for his arrest.
Later, there was a problem finding witnesses to testify in the case as it aged, but the charges were never dropped.
Deputy Solicitor Willy Thompson told Channel 9 Monday that he is now taking another look at the case to see if it can be brought to court, 18 years later.