Last year I discovered that one of my credit cards had been used to purchase a wide variety of different things, including sushi, in a town near me. Turns out it was an employee of my dentist, the person who took my credit card info when I paid the bill. The police told me that she had done this to at least 25 other patients. My dentist was so embarrassed, he didn't charge me for my next cleaning and x-rays.
She racked up over $40K in charges on people's cards. Was apparently caught because of my case. I had used an HSA credit card to pay for the dentistry and that was the only place I had used that card in months. She is now in prison.