If you can get some sort of police report comparing the damage to the cars (paint color, height above ground) that would be great.

Even if you can't--if you are sure he's the guy--you might confront him and tell him that one of the neighbors told you he (or she) saw his car do it. (Is he married, have a live-in girl? Maybe it wasn't him, but his car). See how he reacts.

If you still think he's guilty, tell him you are going to speak to his company commander about prosecuting him for his actions. This is something the armed forces take VERY seriously and should scare him straight. If he still ducks responsibility, follow through.

However, make sure in your heart you are right before publicly accusing him.