A 19-year-old mentally retarded girl was repeatedly raped allegedly by a 59-year-old person for a long time in Thatitooru area under the Bheemili police station limits in the city. The incident came to light after she was admitted to a hospital following severe illness. According to sources, the girl is a neighbour of K. Krishna Rao. Being mentally retarded, she could not inform her parents about it. The doctors alerted the cops about the girl’s condition. After investigation, the police took Krishna Rao into custody. Bheemili police have registered a case and investigation is on.