Brother's BMW M3 in hit and run by unknown acquaintance, looking for advice on how to handle the situation

My brother recently saved up for and purchased a 2003 BMW M3. He's mad about cars and this one especially. A few days ago, while parked at a friend's house, someone backs in to his car in the driveway and then flees the scene. An onlooker thought it was something like a Pontiac Grand Prix, a pretty common car for a high schooler. He thinks he knows who it is as the paint scrape matches the color of a friend's Grand Prix. They and their parents denied the accident but I am somewhat skeptical. The person in question was present at the time, paint matches what was left on my brother's car and they drive a Pontiac Grand Prix, apparently very poorly. (As all high schoolers do) The damage done is pretty extensive to the front bumper and lights, would have to replace the entire bumper most likely? (Not sure) Insurance apparently doesn't cover the type of damage done so it would be all out of pocket for our family. Just generally curious on how I should approach the situation and if there is anything I can/should do to hopefully figure out who caused the incident?Images of car damage: http://ift.tt/2sXNf0c via /r/cars http://ift.tt/2tHgAt8