Its probably worth noting that currently these are unsubstantiated allegations. Its pretty pathetic that there's no proper inspection/investigation regime in place though since these are the kinds of things that need to be resolved quickly.
Its not like there isn't form for this though. Some of the ex military/current detention centre bouncers have been out in numbers at reclaim australia rallies. Nevermind the fact that companies like serco who run these kinds of facilities have form also.
I concede that in itself doesn't constitute proof obviously, but its at the point where you actually expect it to happen.