Sure it has, just look at infamous ECW nigger New Jack and his long history of legitimately trying to injure the guy he's working with and straight up attempting murder in the ring twice.

I hadn't heard of him. Reading about him sort of proves what I'm getting at though. The first was a hardcore match where nobody knew to step in and should be a higher trust setting by definition. The second one had to be stopped by an actual cop who happened to be there, but only after he stabbed the guy in the head 9 times. This guy really does fit the mould though:

"the more they called me a nigger, the angrier I got and the more I beat the guy up." - after first incident

Someone said the N-word so it was okay.