RE: To good to be true...
Definitely get the DNR involved. Take pictures of the deer carcusses for proof and show them. There's no reason for a headless carcuss except for poachers. That should get them interested big time!
Talk to her son and see if he has any friends out there hunting. You do not want to tick him off so he goes back to mommy and has her revoke your hunting priviledges.
Also, if you need help I would not be afraid to contact MDbohunter. He is an ethical hunter and would make a good ally to go up against these poachers.
Set up some deer cameras and make sure they are well hid. You might catch one of these poachers in the act on film. That would be great!
Good luck!
Matt