Apparently an officer in Sanford FL (pop 57,000, 30% African American) was fired for this (and quit before termination). I don't know if he was on duty of off duty (or why it would matter).
A cop with a clean record gets on stage at a concert and shouts, best I can tell, "Let the journey begin!" I thought this is what touchy-feely community police are supposed to do. Now I hate death metal as much as the next guy. Probably more. And I'm sorry if you clicked on that link unaware that Jesus would promptly flee the room. But, seriously?
You may remember Sanford as the the place where George Zimmerman killed Trayvon Martin and got away with it. Maybe there's a backstory we don't know about. At least we don't have to rehash the pointless "I wonder if this would would have happened if the cop were white?" debate. The cop was white; the chief who fired him is black. I wonder what would have happened if a black cop had introduced Ice-T's Cop Killer. I wonder if... Oh, never mind.
Perhaps the real issue is that Chief Cecil Smith is offended by anti-Christian lyrics? I don't take lyrics at face value; it's a song! But maybe in small-town Florida, singing for Satan is still seen as a threat to our Lord and Savor the the moral fiber of America? I don't know.
Anyway, this is further reason cops are paranoid. And also why police unions and due process have a role in protecting the job of civil servants.
(thanks to Julio)