I'm looking for justice for my bro

My brother was shot in the head by an off duty cop who praised himself a warrant officer and connected. He was too violent that he wanted to shoot back to the cops who came to the scene.... how may I get justice. My little brother was just as innocent as the whole community witnessed. All happened in Clayville on the 19th of April 2019. And the ****er cop is still free . His colleagues are saying that only in court they will find him guilty regardless of his self confession that he brutally shot and ****ed a boy