O'Hara (first name unknown) is the accountant of Julian Decker, who signed off on fraudulent records of Decker's tax returns to hide he was raping and prostituting women he hired as models in his independent work.
After Decker was murdered, O'Hara's cons were revealed, and he confessed to what Decker's activities were. His legal status is left unknown. (L&O: "Skin Deep")