The TBM must have been trying to send a 'message' to someone. If they wanted to simply 'disappear' the bear they would have tied nerf bricks to his feet and dropped him into a hole in the Lake.

Careful, you could wake up next to a rocking-horse head.

Did you check the ditches? Maybe he was in an accident and coming to your house for help and was taken by the elements. Wait, is that a tire track across his back?

Sounds like a job for Stuffed Crime Scene Investigation. From the tuft of fur to his left, I think we can surmise he may have been running from his attackers.