Authorities in Washington, D.C. have launched an internal affairs investigation into statement discrepancies related to Chris Brown's 2013 assault case. The Kiss Kiss hitmaker, who is still on probation for his 2009 attack on then-girlfriend Rihanna, was charged with a misdemeanour in October (13) after he was involved in a fight outside a hotel in the city. He has pleaded not guilty, and recently rejected prosecutors' offer to reduce the count to simple assault if he changed his plea after his lawyer asked to see surveillance video footage from the night of the incident before entering negotiations. Now it has emerged that police investigators have launched an internal probe amid claims that an officer who had been at the scene of the alleged clash had told one of Brown's acquaintances that the singer had never punched the alleged victim. According to police records, the R&B star's unidentified pal relayed the conversation to detectives in charge of the case, only for the cop in question to deny even speaking to the witness. However, a uniformed Secret Service agent, who had also been on the scene, spoke out in support of Brown's affiliate after overhearing the reported chat - and now the conflicting evidence is under review. A statement released to The Associated Press from Police Chief Cathy Lanier reads: "We are aware of the discrepancy among witness statements in the Chris Brown case. This is not uncommon in cases with multiple witnesses involved. We have received no complaint of misconduct on the part of any officer in this matter."