Numerous doctors and other licensed medical staff working for the Oklahoma Corrections Department have less-than-spotless pasts, public records show. Many former prison medical staff had checkered histories, as well. The group includes doctors with long struggles with substance abuse, a physician assistant disciplined for writing fictitious prescriptions and a former high-ranking official who left the state after allegations of sexual harassment were made by three female employees. Such medical professionals, those with checkered pasts, commonly work for state agencies such as the state Corrections Department, said Lyle Kelsey, executive director of the Oklahoma Board of Medical Licensure and Supervision.