This sort of thing happens more than people would like to believe. The following is a case of a 40 year old woman brought in for DWI. The woman refused to take a breath test while on surveillance camera. The policeman threw her against the wall then turned off the surveillance camera, when the camera was tuned back on she was lying in a pool of blood, had a busted cheek bone and broken teeth. the feds are now involved.
The Link
The Link