Cape Town - A Mitchells Plain police officer is being investigated by the Independent Police Investigative Directorate after a woman claimed to have been raped while in custody.Spokesperson Robbie Raburabu confirmed the complaint was laid on Tuesday by a 34-year-old woman who had been arrested for drug possession on Sunday."It is alleged that a 38-year-old detective sergeant booked the victim out of the cells to the fingerprints room where he offered her his private cellphone to call her husband. After the call was made he then demanded [that she] return the favour," Raburabu said."It is alleged that he used his finger to penetrate her. When he was done he took her back to the cell."Police spokesperson Captain FC van Wyk said a criminal case had been opened against the officer but was unable to confirm if the officer had been suspended or not.