If you have bruises get pictures of the bruises. Have a third party take the pictures so you have a witness to the bruises to being real. If you have an attorney representing you in the criminal matter tell your attorney what happened and that you want to pursue it. You will then need to submit a report and complaint to the law enforcement agency the officer is from. That will get you started but there are many different steps you will have to take. It is a civil rights matter against a government agency. It will be considered a government tort claim and must be filed within 6 months of the event. It is also a criminal matter. The first step is to get pictures and submit a police report.