Regarding theft and Robbery of my silver jewellery

Hi my inlaws are staying in Chennai for past 45years..one year back due to personal reasons they were traveling so often. On nov 7th 2018 we got a call from our servant stating that some people entered our house nd robbed our jewels . immediately we raised a complaint to Mylapore station, DC, AC police came home and try to find the finger prints but unfortunately not able to find . they promised will find within a week ..but Asusual no response ..we even complaint to commissioner officer..but still no response from their end. We even know the culprits , we know it's all done by our servant, but police refused to enquiry the lady servant . Kindly help us what to do know..