Not just in the medical field.
Company I worked for some years ago got taken when someone somehow slipped through the background check process, which included fingerprints.
Still not sure of the entire story, but apparently she had convictions for fraud and ended up trying to run another one at the credit union. Fortunately she didn't get far before she was caught, but it was by fluke that a supervisor just happened to be listening in on her phone service call, and that set off a larger investigation that got her.