30 coupe and Nightstalker have the answer.
Having done a short stint in federal law enforcement I can cettainly attest that at least at that level, people are held to a higher standard. If you can contact his comander, especially if you can provide hard data like the make, model, color and license number of the vehicle it will go a long way in helping your case.
I suspect that what will happen will be one of two things. Either way, the officer in question will get called on the carpet and have to explain himself which he may or may not do to his boss's satisfaction. The key though is that his boss won't forget it.
Now in the first case, the officer will buffalo his boss to get out of trouble but out of fear will not come back to hunt your private land because he will be afraid to.
In the second case, he'll be ticked off and after he BS's his boss, at some point he will be back to hunt just because he's that kind of guy. That's where you come in. If you can catch him in the act AFTER you've been to his boss you've pretty much got him. May be easier said than done though.
Also, if you can, when you do go to his boss the first time, you may be able to get some sort of written statement of your complaint. If you catch him there again and you go to his boss and by some chance he doesn't want to do anything to his employee for personal reasons, I'd take to the local paper or at least make that threat.
I know this sounds like you are going out looking for trouble but the way I see it is if you know you are right, you shouldn't back down to him just because he's a police officer. Kinda the old "All it takes for evil to triumph is for good men to do nothing."
But through it all, don't loose your cool and be sure to act responsibly.