My first guess is that's it's either a current or former co-worker and for what ever reason they're ticked at you. So try and figure out 1 who you fired recently, 2 somone that was passed for promotion, 3 someone the for what ever reason doesnt like your taste in cars. Something similar to this went through my neighborhood recently only it was rocks and $215.00 later I replaced the rear window of my daughters car. Our neighbor unfortunately didnt fare so well, Window, door lock and cable, back of seat, dash panel and Bose stereo. After talking with the investigating officer it's a somewhat patterened act going through different neighborhoods, The suspected people are from (not to sound discriminatory) the low income section 8 areas that dont really have a chance in life and dislike white ppl in the suburbs.
If you find them kindly lay them on the ground, place there arms over the curb and jump. Or a hammer and dolly to the hand would also work.